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When friends look at pictures of some of my 3-D models, one of the most repeated questions I get asked is, "Did you draw that?" I don't really know how to respond more than, "No, I built it." A face of confusion usually follows as they know it's not a photo, but now realize it's also not a drawing. "So you didn't draw it?" "No, I built it piece by piece." "From what?" It becomes the "Who's on first?" of art.
So I decided to add a page to my site explaining how this is done, using one of the models from my gallery, Old Buildings. I will go step by step (in a basic way) in visualizing, building, texturing, and lighting the model, and hopefully answer a few questions in the process. The project in question was done using Cinema 4-D, the most powerful of my 3-D programs.
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Initial research and ideas...
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Some of my projects come straight out my head, with no visual reference. In this case, I might make a sketch or two, with measurements listed and some ideas written out. In other cases, I might work from the photo of something I see in a book or magazine. In still other cases, I might actually go out and take photographs of things I think would be fun to model.
In the case of my "Old Buildings" model, I actually took photos of the buildings that seemed they would be a challenge to model. The buildings are located in downtown St. Louis, Missouri, across the street from the hotel I was staying in for the week. Below are small versions of some of my reference photos. Note that my project was not meant to reproduce these buildings exactly as I saw them, but to use these buildings as reference for my own run-down buildings.
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Modelling the Pieces...
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After looking through the various photos, I will generally decide measurements and start modelling the individual pieces. I am going to start with the door area of the building. I'm not going to go into a detailed point by point building process, as this is not a how-to manual. I'll just give some general ideas on how I go about building the pieces.
1. I started by building the very basic parts, the two steps and the main wall. The steps were made simply by inserting two cubes. Almost all 3-D programs have some basic shapes which can be used, so not everything has to be modelled from scratch. Each cube is given a size, in this case the bottom step being 131" x "40.5" x 6" and the top step being 102" x 31.5" x 6". Position them correctly, and we have a small staircase. The back wall is simply a flat plane with a doorway cut out of it. From this cutout, small indentions are made so that the wall has some depth.
2. To make the column tops, I used what is called an extruded spline. What I did was to create an outline of the object, as can be seen with the yellow/orange line.
3. This spline is placed in an extrusion object which gives the object depth in the shape of the lines I drew before. As you can see, the blue object is about 18" deep in the shape of my lines.
4. The moulding around the top is done in much the same way, but using what is called a sweep. First, the general shape is defined using another spline, which you can see with the yellow/orange lines. Another spline is drawn to show the profile of the moulding, as in all the roundings and indentions and whatnot. These two items combined together create a shaped moulding as can be seen in section 4.
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Putting the pieces together...
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After modelling each piece, I generally put it into place and start building the whole picture. In the picture below, you can see the wireframe image, with several more parts added than what I showed above (the letters, doors, and windows). Below on the right is a quick render done of these pieces.
On the right, I have modelled the rest of the building, piece by piece, and placed them all together to create a full building. So far, it is just white...there are no textures or lighting assigned.
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Texturing the models, part 1...
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So far, all of the items are white. Nothing has any real feeling to it, and obviously it doesn't look real. Where we go from here is to texture each and every item in the scene. This can involve anywhere from one to one-hundred or more textures. This building in particular contains 55 textures, from bricks and old wood to glowing neon and cigarette ashes. Each texture is also created one by one to be applied to each item. First, we'll look at the making of the texture for the ashtray, using completely built-in material generators.
On the left, you see what the ashtray looks like completely textured. It has a green-painted body which has rusted over, a chrome top which has also rusted over, and a tray of black sand and butts. In order to make the texture for the body, I used a layered color scheme. As you see in the middle image, I made the color for the green paint. Using one of the built-in effects, I made kind of a mottled green, so that it's not all the same color, but sort of faded in parts. I did the same thing for the rust, making it dark brown and reddish colors. Instead of the faded look of the green paint, the rusty reds are sharp changes, as rust would be. Then, in the right window, these two color schemes are combined using a mask. The green paint is the base color, as it would be. The rust is then blended in on top. Using the mask channel, I can make the rust appear only in certain areas. All of these options and schemes are fully selectable and controllable. Adding the same kind of thing in the bump channel gives the object some depth and surface anomalies instead of being a perfectly straight object. Add a little specularity to allow reflected light, and we end up with a rusty, green-painted body. The rusty chrome was done using the same processes.
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Texturing the models, part 2...
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In the last step, we saw textures that were created using built-in generators in the 3-D program. However, some models require precision and realistic-looking textures. This requires that the textures be hand-painted or derived from photos. In my building scene, most of the textures are hand-painted textures, as I required water drips, dirt patches in certain places, and cracks in the walls.
On the left, you see the bottom part of the building as it appears, textured and everything. To the right are a few of the textures I created to use on this model. These were all hand painted using a graphics tablet in my 3-D program's painting environment. The great thing about it is that you can paint either straight as usual, or you can paint directly on the model itself, so you can see exactly what is going on.
In the middle is the map for the concrete around the door. As you can see, in addition to the basic color of the concrete, there are several patches of dirt along the sides and around where the door frame falls into it. To the right of that is the base map for the walls on either side (where the ornate lamps are). The horizontal grout was added as another layer later. To the far right, on the bottom, is a map to define the water stains under all the letters above the door. To the far right, on the top, is the color for the doors.
Below is an example of how the color and bump maps come together to make a full material. On the left, you see the grayscale bump map, used to define cracks, chips, or general roughness. In this case, we have the roughness of the old wood, and some chips out of the paint into the door itself. In the center is the color map for the same area of the door, showing the color of the door and where the paint is chipped, as well as dirt in the edges. To the right, you see the result of both put together on the actual model. Now you can see a rough door, with paint chips, and dirt on the corners and edges.
In addition to color and bump, there are plenty of other options to create the perfect surface. We have reflections to make the object reflect what is around it (like a mirror), specularity to make the object shiny or dull as far as light goes (like the difference between a shiny plastic ball or a rubber ball), transparency and alphas to make the object see-through, glow to make an object appear to glow, luminance to make an object appear to light up (like neon or something), and diffusion for adding dirt or other effects. All of these added together, each with their own settings, and we can make the perfect surface. To the right is an example of some different uses of materials applied to some objects.
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Final lighting...
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After everything is built and textured, we end up with a full scene. But if you look at the image to the right, it still doesn't look very real. Time to add lighting. Lighting in the computer environment is even more contrallable than in real life, allowing for effects of any kind to be achieved. I can use directional lights, omnidirectional lights, special shadows, visible light, any color, even patterns in the lights. When all is said and done, we end up with a fully modelled, textured, and lit scene. Even though this scene is not finished, it still gives a very good idea of what can be accomplished.
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