Desktop 3 - Presentation Guide
Materials - Access ---- Materials dialogue box ---- Standard Materials ---- Granite Materials ---- Marble Materials ---- Wood Materials ---- Materials Library ---- Material Attachment ---- Materials - Bitmaps ---- Customizing and Tricks
|1Materials - Access||1-7 MATERIALS|
How do I get this toolbar?
You can also acquire access to these commands from the View pull-down menu. From the View pull-down menu, pick Render > and cascade to Materials...
|Render pull-down menu
Illustrated to the right, I show the Render pull-down menu which consists of all the same tools as those found on the Render toolbar. In this Part we will be discussing what may prove to be the most difficult aspect of the Rendering process: Materials.
Below, we will look at a broad range of possibilities working with Materials for simple Colors, Complex Colors, Textures, Transparencies and photo-realism. Though a lot of amazing work can be done with the Materials, it is important to keep in mind what the final product will be used for, how it will be presented and how much time you have to produce it.
In many cases, it actually serves a project better to keep Materials simple and plain. This can be seen as a style in itself much like hand drawn renderings are done in styles. At the time of this writing, I have noticed that the big architectural firms are currently rendering with a lot of pastel Colors with varying degrees of opacity. In the early years of architectural rendering, "photo-realism" was a goal of many renderers but over the years students with artistic backgrounds have illustrated that computer rendering styles are not only valid but quite astounding. Clients have often asked me to tone down the "realism" to avoid drawing attention to elements of a design that are either incomplete or simply less attractive in a rendered image than in reality.
Two Types of
|2Materials dialogue box||2-7 MATERIALS|
|Materials dialogue box options broken down
The Materials dialogue box, illustrated to the right, is the primary tool for managing materials in AutoCAD and Architectural Desktop. Through this dialogue box you can track the Materials that exist in the current drawing, create New and Modify existing materials, access the Materials Library dialogue box and associate Materials with objects, Colors or Layers. The default Material for all objects is the *Global* Material which is automatically Attached to all objects until another Material has been Attached. The *Global* Material can be Modified as a Standard Material but cannot be renamed.
The Process of working with Materials involves the following steps:
1. Create a New Material or Load a pre-defined Material from the Materials Library.
2. Modify the Material to suite your specific needs or skip to step 3.
3. Attach the Material with 3D Objects in your current drawing by direct Attachment, by Color ( AutoCAD Color Index (ACI) ) or by Layer.
4. Render the work to test the effect of your Material on your 3D Objects.
After running a Render test, you may discover that the Material requires Modification. You may also discover that the Mapping ( orientation and scale ) of the Material requires adjustment. We will discuss these issues and more below.
|3Standard Materials||3-7 MATERIALS|
|New Standard Material
One of the most difficult Materials to make is one of the first Materials I looked for in the Material Library only to discover that it doesn't exist. If you need to create the effect of Water in your Renderings, you will have to invent your own solution. In the following discussion, we'll take a look at some tricks for making Water and learn quite a bit about making Materials at the same time.
On the Materials dialogue box, illustrated left, use the Standard Material type and Select the New... button. This will automatically activate the Modify Standard Material dialogue box, illustrated below right.
|Standard Material dialogue box
On the Modify Standard Material dialogue box, you can work with each of the Material Attributes by setting the Attribute radio button. To the right of each Attribute, you can use the various settings and controls to define the appearance of the active Attribute.
Material Name - use this text field to type in a name that best describes your material. You can use up to 16 characters ( or numbers, spaces, etc.) and there are few, if any restrictions, on the use of spaces and wildcards so "-", "/" and "*" are all allowed.
Ambient - this radio button allows you to use the adjacent Value and Color options to set a material's Shadow Color. Put together with Color/Pattern and Reflection, below, you can control the full spectrum of how a material will look from highlight through to dark shadow.
Reflection - this radio button allows you to use the adjacent Value, Color and Bitmap options to set a material's Highlight Color. This Attribute is also how you control the reflectivity of your Material and what is reflected. By using the Mirror Color option, for example, you can create a perfect mirror effect. By using the Bitmap option, you can specify a "fake" image as a reflection.
Roughness - this radio button allows you to use the adjacent Value option to control the size of the Reflection highlight or "smoothness" of your material. A lower value, smoother, creates a smaller but brighter appearing highlight that creates a sensation of a smoother object. A higher value spreads the highlight out and makes an object appear more flat and rough. Think of the difference between how light appears on a cue ball and blue jeans.
Transparency - this radio button allows you to use the adjacent Value and Bitmap options to control the opacity of your material. The Value control allows you to set the Transparency between 0 ( no transparency ) and 1.00 ( completely clear - no opacity ). The Bitmap option allows you to introduce an image as a source of determining non-transparent images within a transparent material. This is how you turn a solid 3D object into a chain-line fence, for example.
Refraction - this radio button allows you to use the adjacent Value option to control the optical distortion of light as it passes through mediums. Be careful with this option because the Value control can be set between 0.010 and 100.0 with 1.00 as normal. Refraction affects Transparency and has to do with the optical effect we often observe when we look at a jagged spoon in a clear glass of water. Values below 1.00 refract opposite those above 1.00.
Bump Map - this radio button allows you to use the adjacent Bitmap options to set an image file for use as texture in your material and control how intense the "bumpiness" value should be. A Bump Map works off of the light and dark regions of a raster image to create a 3 dimensional quality in your materials; the lighter areas appear as high spots and the dark areas appear as low recessions.
|New Material - Color Options
Illustrated to the right I show the options available for controlling the Color of the Color/Pattern Attribute.
Value - this is a simple range control that can be used to fade the color from 100% to 0% pigment. Depending upon the Ambient and Reflection Colors, you can blend in more or less of these Colors. In the case of a Blue Color/Pattern and a Green Ambient Attribute, you can bring in more Ambient Color by reducing the Value of the Color/Pattern Color.
Lock and Mirror - these checkbox options are not available for this Attribute.
Color System - this drop-down list allows you to work with the Color palette through the Control of the RGB ( Red, Green, Blue )or HLS ( Hue, Lightness, Saturation ) controls. Both are similar but allow you to "dial in" the specific Color you seek through different control types. I prefer to use the Color Swatch box to the right of the Color System to access the Color dialogue box ( see above ) and simply set my color there. It should be noted that by the time you get to paper the likelihood of getting the same color on paper as that which you have carefully selected here, is about the same as being struck by lightning ( that's my unscientific estimate ). In other words, don't worry too much about exact colors and run print tests early on so you don't end up with a hideous green when you expected turquoise.
Bitmap Blend - see Bitmap as Color/Pattern Attribute.
|New Material - Ambient Options
Illustrated to the right I show the options available for controlling the Color of the Ambient Attribute.
The Ambient Attribute controls how a Material appears when light strikes across its surface and creates a darker side. The Color of the Ambient Attribute can be used to change the shade of the Material Color on the darker side but can also be Locked to match the Color/Pattern Attribute Color setting.
Value - see comments for Color/Pattern Attribute.
Lock - use this checkbox to lock the Ambient Attribute Color to that of the Color/Pattern Attribute. Doing this will keep a Color consistent while allowing a change in the shade via the Value setting.
|New Material - Reflection Options
Illustrated to the right I show the options available for controlling the Color of the Reflection Attribute. The terminology can be a bit confusing at first glance since we often think of reflection as one thing: a mirror. In the case of Materials, you can create a perfect Mirror but you can also use the Reflection Color as your Highlight Color and thus present the opposite spectrum of the Ambient Color ( the Shadow Color ).
Value - this is a slightly more complicated range control because it can be used to strengthen or weaken the highlight color but when used with the Mirror checkbox, can also be used to control how reflective the material is. In other words, if you want a perfect Bathroom mirror, use the Mirror Checkbox and set the Value to 1.00 or 100%.
By ACI - this checkbox deactivates the Color options and uses the Colors assigned in AutoCAD / Architectural Desktop by the AutoCAD Color Index. In other words, the Material's Reflection color ( highlight color ) is derived by what has been directly assignment to the object(s) or by the Layer.
Lock - this checkbox locks the Reflection Color to the Color/Pattern Color to provide a non-specular Material.
Mirror - this checkbox set the Reflection Color to the scene and the objects and materials used in it. The Value setting will serve as a Mirror control setting for how reflective you want your Material. Use this option along with a Value of 1.00 for chrome and mirrors. Tip: make sure there are no Bitmaps overriding this setting.
Bitmaps - using bitmaps for Reflections is a way of "faking" a reflection when either none exist or when what does exist isn't what you want. Much to my personal irritation, you will find that most of the default Reflective Materials in AutoCAD and Architectural Desktop have bitmaps as a Reflection Attribute. You can quickly remove them and use the Mirror option instead.
Bitmap Blend - see Bitmap as Color/Pattern Attribute.
|New Material - Roughness Options
Illustrated to the right I show the options available for controlling the Value of the Roughness Attribute. This is the only option available for the Roughness Attribute.
Value - this range control can be used to make a material appear more or less shiny. The range is between 0.00 and 1.00 ( 100% ) where 0 is the least rough or most shiny. It works best in combination with the Reflection Attribute and its Color because you can bring the Reflection Color to a highlight point ( very shiny ) or spread it out over most of the surface the Material is Attached to for a dull appearance.
|New Material - Transparency Options
Illustrated to the right I show the options available for controlling the Value of the Transparency Attribute.
Value - this range control can be used to make a material appear more or less transparent ( opaque ). The range is between 0.00 and 1.00 ( 100% ) where 0 is the most opaque and 1.00 is so transparent that it can be invisible.
Bitmaps - using bitmaps for Transparency is a way creating materials that appear like 3D geometry when they are not modeled at all. A great example of this is a mesh like that of a steel fence; by using a bitmap image of a fence as a transparency map, you can have the material show all black areas between the steel as transparent. You can read more about this under Bitmaps as Transparency Attribute.
Bitmap Blend - see Bitmap as Color/Pattern Attribute.
|New Material - Refraction Options
Illustrated to the right I show the options available for controlling the Value of the Refraction Attribute. This is the only option available for the Refraction Attribute.
Value - this range control can be used to make a material refract light in opposing directions; using the spoon in water analogy, the spoon can be made to look smaller or larger. Since 1.00 equates to no Refraction, values below 1.00 create the effect of objects getting larger while numbers greater than 1.00 create the effect of objects getting smaller. The Value range is between 0.01 and 100. Refraction settings affect Transparency and usually require some Value of Transparency to be effective ( obviously ). Personally, I use this option infrequently and only to create a less than perfect reflection; something like a bit of noise in the reflection.
|New Material - Bump Map Options
Illustrated to the right I show the options available for controlling the Bitmap Blend and File Name of the Bump Map Attribute. Bump Maps are one of the best options you will find to make custom Materials look more realistic or more "alive" because they provide the ability make a material appear three dimensional regardless of what it has been assigned to. In other words, by using the dark and light colors of raster images you can create valleys and peaks in a material.
Bitmap Blend - this range setting can be used to control the strength of the raster image's effect upon the Material. A Value of 1.00 ( 100% ) will create the strongest valleys and peaks possible by the bitmap chosen.
File Name - this text field is used to specify the Name and Path of the raster image you want to use as a Bump Map. By using the Find File... button, you should be able to seek out and select just about any raster image on your machine or network. To use AutoCAD / Architectural Desktop's materials, set the File Type to ".tga" and look for the Texture folder under AutoCAD or Architectural Desktop
Adjust Bitmap - this button will take you to the Adjust Material Bitmap Placement dialogue box where you can use various bitmap settings to control how the raster image relates to the object(s) you assign (Attach) it to. See Adjust Material Bitmap Placement for more information.
|4Granite Materials||4-7 MATERIALS|
|New Granite Material dialogue box
The Granite Material, to me, is really just a noise material where you can specify up to four different colors to create a pattern that mixes them "randomly" like a bunch of pixels. If the pattern is set to a very large scale, then it does not look as random but may still suffice as a quick solution for creating a material that appears complex and more organic than a plain monotone color.
On the Materials dialogue box, illustrated left, use the Granite Material type and Select the New... button. This will automatically activate the Modify Granite Material dialogue box, illustrated below right.
|New Granite Material dialogue box
Illustrated to the right I show the options available for setting the four different Color Attributes.
Value - this is a simple range control that can be used to fade the color from 100% to 0% pigment. Depending upon the Ambient and Reflection Colors, you can blend in more or less of these Colors. In the case of a Blue Color/Pattern and a Green Ambient Attribute, you can bring in more Ambient Color by reducing the Value of the Color/Pattern Color. Since you have up to Four Colors to work with, you may also use the Sharpness Attribute to Blend the Color Attributes together.
Color - with Granite Materials you do not get an option for By ACI, since this material utilizes up to four different Colors to create a Granite-like appearance.
Color System - this drop-down list allows you to work with the Color palette through the Control of the RGB ( Red, Green, Blue )or HLS ( Hue, Lightness, Saturation ) controls. Both are similar but allow you to "dial in" the specific Color you seek through different control types. I prefer to use the Color Swatch box to the right of the Color System to access the Color dialogue box ( see above ) and simply set my color there. For Granite-like Materials, you will be able to use up to Four Colors but you can also set two colors to be identical or simply set one or more Color Attribute Values to zero if you wish to reduce the variety of Colors.
|New Granite Material - Reflection and Roughness
Reflection and Roughness Attribute Value settings work the same way on the Granite Material as with other Materials - see comments under Standard Materials, above, for more information.
|New Granite Material - Sharpness Options
Illustrated to the right I show the options available for controlling the Value of the Sharpness Attribute. This is the only option available for the Sharpness Attribute.
Value - this range control can be used to blend all of the Colors or to sharply define them as distinct pixels. Since 0.00 equates to a complete blend, values above 0.00 create the effect a rougher surface by refining or sharpening the differences in the colors. The Value range is between 0.00 and 1.00.
|New Granite Material - Scale Options
Illustrated to the right I show the options available for controlling the Value of the Scale Attribute. This is the only option available for the Scale Attribute.
Value - this range control can be used to decrease or increase the Color Attributes over the surface of the object this Material is Attached to. Getting the right Scale for a scene is a matter of trial an error. The Value range is between 0.010 and 100.0.
|New Granite Material - Bump Map
Bump Map Attribute settings work the same way on the Granite Material as with other Materials - see comments under Standard Materials, above, for more information.
|5Marble Materials||5-7 MATERIALS|
|New Marble Material dialogue box
Note: these materials will not translate to 3D Studio Viz. Information will come in a future update to this guide.
|6Wood Materials||6-7 MATERIALS|
|New Wood Material dialogue box
Note: these materials will not translate to 3D Studio Viz. Information will come in a future update to this guide.
|7Materials Library||7-7 MATERIALS|
|Materials Library dialogue box
The Materials Library dialogue box, illustrated to the right, is the primary tool for accessing predefined materials. The default Materials Library consists primarily of Standard Materials that have been Modified to use various Bitmap images as their Attributes ( Color/Pattern for the most part ). AutoCAD and Architectural Desktop come with one default Material Library file called "render.mli" and you should find that once you access your Materials Library, this file is automatically opened.
If you do not find a large list of Materials, such as illustrated to the right, check to make sure your program was installed with the Textures Folder. Also, use the Options dialogue box and confirm that the Texture Maps Search Path is set to the proper location of your textures.
Illustrated to the right, I show the process of looking through the Materials Library, finding a Material to use and Importing it into the current drawing. Once a Material shows up on the left pan of the Materials Library, you will be able to use it via the Materials dialogue box ( see below ).
Save As... - use this button to create your own custom Materials Library that you can access through the Current Library drop-down list. You can save .mli files to any folder you want and thus keep them within projects folders.
<-Import - use this button to transfer a Material from the Current Library to the Current Drawing.
Export-> - use this button to add a Material from the Current Drawing to the Current Library.
Delete - use this button to delete or erase any highlighted material.
Open... - use this button to open any Material Library ( .mli ) files that have been created with the Save As... buttons.
Save - use this button to save any Materials that have been Exported to the Current Library from the Current Drawing.
Save As... - use this button to save the Current Library with a different name to a possible new location.
|Bitmap Texture Location
AutoCAD and Architectural Desktop come with a fairly extensive list if bitmap files that you usually access automatically through the Materials Library dialogue box. If AutoCAD and/or Architectural Desktop have been installed with all of the materials, you should find them in a subfolder called Textures.
For some reason unknown to me, all of the bitmaps that come with these products are targa files with the extension .tga. The reason you need to know this is that when you use the Find File... button on any of the Modify Materials dialogue boxes, the default file extension is set to .bmp and thus you will not be able to see any of these files unless you set the Files of Type to .tga.
You are not limited to the materials in this folder nor targa files so you can add all of the bitmaps you want to this folder or even keep a library of folders for different types of materials. Since AutoCAD and Architectural Desktop usually have a default Path set in the Options dialogue box to look for materials in the Textures folder, you may want to work with this folder or Add new folders to the Texture Maps Search Path.
One thing you must keep in mind when creating Materials and working with custom bitmap images is that just like Xref's and Image Ref's, bitmaps are not imbedded in the drawing file. Each time a Rendering process is run, AutoCAD\Architectural Desktop must look for the bitmaps that have been used within the Materials Attached to objects in the current drawing. This also means that if you want to copy or move a project, you must track the bitmap files as well.
|8Material Attachment||8-7 MATERIALS|
Illustrated to the right is the Materials dialogue where among other things, you use the Attachment or Association tools to put the Materials on the objects in your drawing. Once Materials have been Imported to the Current Drawing within the Materials Library dialogue box, these Materials can be Attached, Duplicated and/or Modified on the Materials dialogue box.
Since working with Materials from any Material Library must be done through the Materials dialogue box, illustrated to the right, it makes more sense to use the Materials Library... button as a means for accessing the Materials Library dialogue box. It is for this reason that I never use the Materials Library button or command; I do all Material work through the Materials dialogue box.
Preview - use this button to see a rendered preview of the highlighted Material. The Preview drop-down list offers two objects that can be used for the Preview: Cube and Sphere.
Materials Library... - use this button to access the Materials Library dialogue box and Import Materials into the Current Drawing for use through the Materials dialogue box.
Select < - use this button to identify the Material Attached to an object in the current drawing. This process will also identify the type of attachment: Attach, By ACI or By Layer.
Modify... - use this button to access the Modify [Material Type] Material dialogue box for changing all of the Attributes that define a Material's appearance and mapping behavior.
Duplicate... - use this button to make a copy of the highlighted Material. Using this button will activate the Modify [Material Type] Material dialogue box dialogue box automatically with a copy of all of the Attribute settings of the highlighted Material but you will need to specify a new Material Name.
New... - use this button in conjunction with the New Material drop-down list to create new Standard, Granite, Marble or Wood Materials.
Attach < - using this button allows you to leave the Materials dialogue box temporarily while you Select objects in your drawing that you want the current Material "attached" to. The problem with this methodology is that it is very difficult to track materials and objects. The only way to know what material an object has is by Rendering it or by using the Select < button.
Detach < - use this button to Undo the work done with the Attach button.
By ACI... - using this button allows you to work with the Attach by AutoCAD Color Index dialogue box where you can manage the attachment or association of materials with Colors - see discussion below.
By Layer... - using this button allows you to work with the Attach by Layer dialogue box where you can manage the attachment or association of materials by Layer Names - see discussion below.
|Attaching Materials by AutoCAD Color Index (ACI) dialogue box
Illustrated to the right is the Attach by AutoCAD Color Index dialogue box where you establish links between Materials and Colors in the current drawing. To Attach a material to a Color, highlight the Material and the Color before using the Attach -> button.
For typical AutoCAD 3D objects, such as those created by Solid and Surface Modeling, using this technique is probably not as beneficial as using the Attach by Layer technique.
For many of Architectural Desktop's 3D objects, such as Doors, Curtain Walls, Windows, Stairs and Railings, using this technique is probably the most logical way to proceed since all of these complex objects come with predefined Color Components but not unique Layer Components.
Illustrated to the left, I show an Interior Door and the default Colors assigned to it by Architectural Desktop ( using a default template for Imperial units ). Since all of the Components defer to the Layer Key for the Door object, they will not be separated into various Layers. Therefore, we must use the Colors for each Component as a way of Attaching Materials. This means that if you Attach Glass to Color 141, for example, all 3D objects assigned Color 141 will Render as Glass.
There are 255 Colors to choose from in every AutoCAD/Architectural Desktop drawing so you can use 255 Materials with this technique.
|Entity Properties -
Object Color Chart
In ADT you should notice that objects will change color when the View or Display is changed. Usually the most dramatic color changes occur when switching from 2D plan to 3D Model. In order to keep track of all these colors, I have assembled a long chart to show what colors have been used and which ones are free. This should help you to modify or add new object colors without getting into too much trouble. Charting this data is exhaustive so it is not complete but it will be updated periodically.
|Attaching Materials by Layer dialogue box
Illustrated to the right is the Attach by Layer dialogue box where you establish links between Materials and Layers in the current drawing. To Attach a Material to a Layer, highlight the Material and the Layer Name before using the Attach -> button.
This technique is one that I personally prefer because of how I try to manage as much as possible through Layers. Having Layer Names that identify the object types make the process of managing Material Attachment far easier than by Color Index. The problem is that Architectural Desktop manages object complexity through Component Colors as opposed to Component Layers. The reason for this is that we would have a huge list of Layers to contend with if each and every Component had its own Layer Name.
For simplicity, I recommend using the Attach by Color Index technique for all of the complex objects in Architectural Desktop - see comment above.
Illustrated to the left, I show an Interior Door and the modifications I had to make to the Component Layers and Colors in order to use the Attach by Layer technique effectively. All of the Components have been set to unique Layers that have unique Colors. In order to see the Layer Colors on my object, I also had to change the Component Colors to ByLayer.
Unlike the the Attach by Color technique, this technique offers the ability to use an unlimited number of Materials.
Though I recommend using the Attach by Color Index, I personally use the Attach by Layer method a lot despite the irritation of having to modify the Entity Properties of all complex objects. The reason for this is quite simple, I can manage the Materials better and faster by Layer Names than by Colors ( that mean nothing to me ). This process also provides me with the added benefit of using the Layer Manager to turn Components On and Off and change their Colors which is quite useful when working in Shaded Modes.
|9Materials - Bitmaps||9-7 MATERIALS|
|Bitmap Images for use as Materials - Overview
When you get to the point where you need more than colors and more than the default AutoCAD / Architectural Desktop Materials Library has to offer, it's time to begin creating your own Bitmap Materials. The ability to use any digital image that you can create ( see types below ) allows you to recreate reality as closely as the rendering tool will allow. On some projects, clients have supplied me with a bag of samples covering everything from wall applicants to carpeting, ceiling, furniture, fixture and even wall art. If you find that the job calls for such high levels of "reality", you should consider using another rendering program such as Autodesk Viz because the Rendering Engine in AutoCAD / Architectural Desktop is simply not up to par with programs designed specifically to produce Renderings. This does not mean that you should not bother with realism but that you simply need to consider how real is good enough and how real can AutoCAD / Architectural Desktop feasibly go. The other consideration is TIME. AutoCAD / Architectural Desktop's Rendering time is dramatically slower than 3D Studio Viz, for example, and it's amazing how a product can pay for itself simply by being faster.
Illustrated to the right, I show one of the more difficult types of Bitmap Materials to create: a pattern material. In the case of a common brick pattern, the trick is to get a good brick sample and then to crop it so that it comes out seamless. The Array command in AutoCAD is a perfect comparison because it works on the same principle. If you don't set up your linework just right before Arraying, the error is easy to spot.
You can use a digital camera or desktop scanner to capture one or more bricks and then use Photoshop or an equivalent image editing program to edit the image for use in AutoCAD / Architectural Desktop. A pattern like bricks is very difficult because our eyes can easily detect patterns in patterns. If you use one brick for a whole wall, your eye is likely to see the repetitive pattern. If you use a few bricks and the pattern has too much variation in it, your eye will see that repetitive pattern too. In an ideal situation you would have a sample equal to your use but that's not feasible in most cases so you attempt to make the best of it. The fact of the matter is that this is art and not science.
The best news is that there are numerous huge libraries of materials that can be purchased. 3D Studio Viz comes with an enormous library of architectural materials that can also be use in AutoCAD / Architectural Desktop if you use the steps outlined here.
If you are just starting to learn about custom bitmap materials, try something easier than bricks. One of my favorite tricks is to do a screen capture with the Print Screen key and then use it as a piece of art hanging on a wall - see discussion below on Signage and Decals for a similar example of this technique.
Once you have a material prepared, you will need to save it in one of the formats outlined below. The size of the material depends on how clear you want it.
|Bitmap as Color/Pattern Attribute
Illustrated to the right, I show the Modify Standard Material dialogue box. You can access this dialogue box by either creating a New Standard Material or by Modifying an existing Material.
Using the same concepts outlined above under Standard Materials, we can choose to use a Bitmap for the Color/Pattern Attribute for the Pattern portion of this Attribute. To use a Bitmap, simply use the Find File... button to locate and Open any bitmap image that has the three letter extension .bmp, .png, .tga, .tif, .gif or .pcx. To learn about creating your own materials, read Photoshop for Materials.
Once you have entered the path and name of the bitmap material in the File Name text field, you can use the Bitmap Blend range setting to control how this bitmap will blend with the Color you have set and how it will blend with the Ambient Color you have set. To learn more about Color Values and Ambient Colors, read New Material - Color Options.
For a first run, you might set the Bitmap Blend to 1.00 ( 100% ) and deactivate the By ACI checkbox. This will defer the Color to the Bitmap image directly. Should you want a slightly darker brick, for example, you can set a dark Color and adjust the Bitmap Blend range setting to allow this Color to affect the Bitmap.
|Adjust Material Bitmap Placement dialogue
Applying, Attaching Bitmap Materials to architectural objects can be a tricky job. The primary problem has to do with the scale of the bitmap image and the scale of your architectural objects. Since we are definitely not going to change the architectural objects, we have to work with the Material Bitmap Placement.
On the Adjust Material Bitmap Placement dialogue box, illustrated to the right, you can control where a bitmap is located on an object, the scale of the bitmap on that objects, if it will be tiled or a single image and the if AutoCAD / Architectural Desktop should automatically attempt to determine the Axis of orientation for the material on your objects.
U and V - these are simply mapping terms for X and Y. In mapping, there is also a term for the 3rd Axis called W and thus you have U,V,W for bitmap orientation; not to be confused with objects using the UCS and X,Y,Z coordinates.
Offset - use these number fields to move an image left and right or up and down relative to the object(s) it has been associated with. You can use this option to align the mortar of a brick with the exact edge of a Wall but I find that type of accuracy incredibly tedious. I typically use this option when applying a "decal" on a surface; something like a colored rectangle with an image or piece of text in the middle to be Rendered at a specific point on an object.
Scale - use these number fields to control the number of times the image is repeated over an object, if tiled, or how big or small the image is. The larger the number, the bigger the image on the object(s) with less tiling. To find the right scale, use the Object Size number field - see below.
Maintain Aspect Ratio - use this checkbox if you want the U and V values to remain proportionally locked to the current setting. In other words, if Scale is set to U = 1 and V =1 then the Aspect Ratio will keep that ratio and you will only need to type in the Scale in either of the two Scale value fields.
Object Size - use this value field to set a dimensional height for the cube or diameter for the Sphere. The value used is directly proportional to the units used in your drawing so if you read 1 as an inch or millimeter, then that is what you will see relative to the image. In an Imperial drawing, for example, you can set the cube to one square foot by typing 12. The trick is to set a working size relative to your material and then work with the Scale to set it correctly for your object(s).
|Adjust Material Bitmap Placement - Scale
Crop - checking this radio button uses just the one bitmap. You can use this option for applying a "decal" to an object, for example, where you do not want more than just the bitmap scaled and located according to your needs; much like a postage stamp on a piece of paper.
Fit To Object - checking this radio button stretches the bitmap out to cover the entire surface of any object it is applied to. The use of Offset and Scale can still be used to control how the stretch appears. This is a great option for objects whose image you have in exact form, like wall art, television monitors, posters, books, etc.
Use Auto Axis - checking this option can prove to be one of the most useful features in mapping or one of the most troublesome. It uses the positive XYZ directions of the objects that this material is applied to to determine the "front" face of a material and thus you could end up with backwards material. Generally, this only proves to be a problem with Bitmaps that have a direction such as artwork, text, television images and posters. When using the Mapping tool you may want to uncheck this option because of the contradiction it creates if you are physically defining the Mapping Coordinates and Projection. I find that Auto Axis causes problems for all but the Planar Mapping Projection. Note: the Scale values usually have to be set much lower when using the Mapping tool.
|Bitmap as Reflection Attribute
This option should be as magnificent as it is in 3D Studio Viz and Max but unfortunately it isn't. One of the primary problems with the use of a Bitmap as a Reflection Attribute is that there are no controls for how it is mapped to the objects;i.e., there is no Adjust Bitmap... option. This means that the bitmap position, scale and orientation are automatically determined and more times than not, the automatic placement is not very good.
Using Bitmaps as Reflection Attributes works best on Spherical objects and provides the types of results you would expect on all objects; a complete image. On Cylindrical objects, the image is distorted because it is improperly mapped for a cylinder but can produce an interesting effect. On rectangular objects, the image is usually unobservable though you will pick up a sampling of its color. This means that if you use a "sky.tga" image for a Reflection Attribute on a Curtain Wall, for example, you should find a tint of blue but little more ( no clouds, no variation ).
If you activate the Mirror option, that type of "true" reflection tends to lighten the effect of the bitmap image.
|Bitmap as Transparency Attribute
There are numerous architectural objects in the world that are impractical to model correctly because the detail is too high and the value to the project too low. An example of this is a chainlink fence, illustrated left, where an ADT Wall object can be used to create the physical dimensions of the fence but not the physical appearance. In a situation like this, you can use a bitmap of a chainlink fence to create the illusion of a meshed fence. The process is nearly identical to that discussed above, Bitmap as Color/Pattern Attribute, with the exception of how the bitmap is colored and used as a Transparency Mask.
Illustrated to the right, I show how the black background of the chainlink bitmap image can be used as a transparency mask for the actual image set by the Color/Pattern Attribute. Since the bitmap image was already set with a black background where transparency is required, it can be used for both Color/Pattern and Transparency Attributes. In some cases you may have to use two different images since the background must be black for the transparency mask.
To make the Transparency bitmap work most effectively, you will need as much of a Transparency Value as you can get ( 1.00 or 100% for full transparency ). The Bitmap Blend value will also affect the transparency by affecting the ration between the image and the black background; i.e., the lower the blend, the more transparent the whole image and the higher the blend, the stronger the transparency of only the black background area.
This sample chainlink fence with posts comes with the default AutoCAD and Architectural Desktop texture library: "fence.tga". Since there are no Chainlink fences in the default Materials Library, you will have to create your own as discussed here. Unfortunately, there are no other chainlink fence bitmaps in the default texture library; this one comes with posts that you may not want to use.
|Bitmap as Bump Map Attribute
One of the best tricks in the world or Rendering involves making Materials do the work of Modeling and the Bump Map is one of the best examples of this type of tick. A Bump Map uses the light and dark areas of a bitmap image to create a type of distortion in the Material where dark areas appear closer to the true surface of the object and white areas appear raised.
Illustrated to the right and below, I show a common architectural application of a Bump Map used to create the effect of a standing seam metal roof. By using one of the default Metallic Materials, all that is required to make it work for a roof is to add a Bump Map as illustrated to the right. At its most basic, a simple light line next to a larger area of black would do the trick and you can learn more about this by reading Photoshop for Bump. In the this Bump Map example, however, I show that you can make them more sophisticated so they produce a more realistic effect. In my example Bump Map Image, I have White Lines for the standing seams but I also have a wider White line for the ridge.
Since my Bump Map Image is pure Black and White with no shades of Gray, the Bitmap Blend Value does not need to be very high in order to produce a believable seam. Shades of Gray on either side of each seam could have been used to create a more Filleted look to the seams but in many cases such extreme detail is not necessary.
The biggest problem with Bump Maps is getting them to map correctly and this can be controlled with the Adjust Material Bitmap Placement dialogue box as illustrated above. In the case of my example Bump Map Image, I have an image perfectly matched to my Architectural Desktop Roof object so I have used the Fit To Object Map Style and uncheck the Use Auto Axis option so I don't get this material on the fascia where I don't want it.
Using Fixed Scale vs. Fit To Object is really a matter of how the Bitmap has been designed and in many cases you will use Fixed Scale so that you can use the Scale values to adjust the image to match the dimensions required in the Rendering. If you use Fixed Scale however, don't expect to be able to create and use a Bump Map Image as complete ( with ridge seam ) as this example.
|10Customizing and Tricks||10-7 MATERIALS|
Illustrated to the right is an example of what I like to refer to as a decal because it is a bitmap that appears to float over other materials due to its transparency. Though it is possible to create a single Material that can function as both primary surface material and decal, the work involved is too tedious for me to justify a discussion here. Instead, simply create a 3D Object right where you want your decal or signage and place it a tiny fraction of an inch or millimeter above the surface below it. If the distance is too great then you will cast shadows onto the surface below the decal.
In the illustration to the right, I used a 3D Face since it consumes a very small amount of memory and is basically an infinitely flat 3D object ( just like a decal ). The important thing to keep in mind is that its size and orientation will affect how the Material Maps to the Surface.
By orienting the UCS icon such that the Z-axis faces in the direction I wanted the text to read ( called the Normal of this face ), I assured that I got a proper mapping orientation ( text left to right ).
By drawing a 3D Face approximately the size I wanted the decal while keeping it relative to the bitmap image ( aspect ratio ), I assured that I got a proper fit along the X and Y axes.
And finally, by using the Fit to Object checkbox on the Adjust Material Bitmap Placement dialogue box for this Material, I assured that the bitmap would be stretched out perfectly across the surface of my 3D Face.
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spell checked on Jan. 24, 2002