photo texture modeling

Creating realistic image maps for your models can be very aggravating, particularly if you are seeking something very detailed and complex. I've found that it's often easier to work backwards. That is, gather photographic source material and create a model to match the image. For example, when creating a brick wall the average 3D artist will simply take a stock brick wall image map and place it on a simple plane. While this is very fast, it's rarely effective at convincing the viewer that the object is real. Why? Simply because the object lacks depth. Sure, you can place a bump map on the image map to create the illusion of depth but this won't hold water in the majority of cases. If you rotate the camera at any angle other than looking directly at the object you'll find the bump map will merely flatten itself out, making the object appear unrealistic. This can be a real problem when animating the camera in a scene. The object will go from realistic to unbelievable in a matter of seconds.

OK, so what's the answer? Well, it's that source material you gathered. To create a realistic brick wall you'll need to use the image map as a template for creating a detailed model to match. Basically, you bring the image map into your modeling program an build the actual bricks to match the image. Sure, it's more work but the results are amazing. You'll end up with a model that's completely photorealistic, even to the most discerning of eyes. Let's take a look at how the photo texture modeling process works.

Figure 1.1 The brick wall image map Figure 1.2 The image map template loaded in to a 3D program

the photo texture modeling process
The first step in the photo texture modeling process is to get yourself a high quality image of the surface you are creating. In the case of our brick wall example I dug up an old image of a weathered brick wall. The next step is to load the model into your favorite painting program and remove all of the shadows in the image map. The last thing you want is some residual shadow fighting the actual lighting of your scene. Figure 1.1 shows the brick image map with all of the major shadows removed.

Now that you have the image map ready to go, you can load the image into your 3D modeling program as a background image template. Figure 1.2 shows the image loaded into the background layer of LightWave.

The next step is rather simple, yet repetitive. What you need to do is create an object that matches the template. For our example we need to create the individual bricks on the wall by manually placing points and creating polygons. Since we're using LightWave for the example I'll demonstrate how this procedure is accomplished in LightWave. First, select the Polygon Tab and then the Create Points tool. Now move the cursor over the place where you want a point and press the Right Mouse button to create the point. Continue this process until you have a brick outlined. Don't worry about including every little detail in the bricks. Just focus on the major areas of detail. The rest will be compensated for by the image map. Once you have the points laid down. Simply press the "P" key to create the polygon. Now repeat this process for the other bricks. When you're completed you should have several bricks like the ones shown in Figure 1.3.

Figure 1.3 The polygons for the bricks

Now that you have the basic brick polygons created you need to add depth to them by using the extrude tool. You should extrude the polygons back slightly so they appear like bricks protruding from the wall. The last step in creating the bricks is to add a very small bevel to the edges of the brick face so they appear a bit more organic, creating specular highlights when rendered. You should now have something resembling Figure 1.4.

Figure 1.4 the final bricks with the bevel.

The next step is to add the plane that represents the mortar seams. This is a simple plane placed behind the bricks as shown in Figure 1.5.

Figure 1.5 Adding the mortar plane.

Now there's just one final step in creating the photorealistic brick wall. Load the model into your rendering program and apply the image map to it. Be sure to apply the same map as a bum map so the little texture details are appear on the finished model. You'll end up with something similar to Figure 1.6.

Figure 1.6 The completed brick wall

As you can see, the brick wall now has 3D depth when the camera is rotated. If this were a seamless image map you could easily tile the model to create a larger, seamless wall. While this technique is certainly more work than simply slapping an image map on a plane, it goes a long way toward making the scene appear realistic.

This same technique can be applied to much more detailed object such as windows, doors, etc. Just about any model can be greatly enhanced through the use of photo texture modeling. While working on the Platinum comic book I used this same technique to create the buildings in the street shots. All of the wall textures and windows were modeled using image maps as templates and then applying the image map as the surface. Try using this technique in your next photorealistic 3D project and you'll soon realize why it an invaluable tool in your photorealistic toolkit.

Bill Fleming is President of Komodo Studio, a 3D studio specializing in photorealism. He is the author of many 3D books, including the "3D Photorealism Toolkit", published by John Wiley & Sons. He also serves as Editor in Chief of Serious 3D magazine, a 3D magazine featuring nothing but intermediate/advanced tutorials for artists interested in taking their 3D graphics to the next level. To find out more about Serious 3D, visit www.serious3d.com If you wish to contact Bill, he can be reached at bill@komodostudio.com.

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