Texturing imported models by Booleans

Last updated: 08.05.2002

If the model you have imported to Bryce consists of a single object that cannot be further decomposed and which contains no texture mapping information - which is the case with models exported from Poser 1 - you have two choices. One is to apply a single material to the entire model. This may be appropriate for some projects, but cannot be used to assign separate regions of skin, clothing etc. (The 'obvious' solution, attempting to map a picture onto the model, won't work because Bryce doesn't have the information it needs to map the picture correctly).

The alternative is to break down the model using Boolean operations, and assign different materials to each Booleaned part of the model. The results of this technique are not particularly good, but it can be used as a last resort.

The basic technique is to make a number of copies of your model, and to select parts of each copy using Boolean operations. These parts can then be individually textured. The following step-by-step example shows how to "clothe" the Poser female nude in a skintight black jumpsuit.

1	Export the figure to be used from Poser.
2	Import the figure to Bryce, using the Import Object command. After you have imported the figure, you may need to rotate it to get it the right way up. You may also want to smooth it to improve its appearance (click the figure, and click on the 'E' that appears beside it. On the dialog box that appears, click the image marked Smooth to smooth the figure). Figure 1: Imported figure
3	Click on the imported figure, and assign it a family color by clicking on the small colored tab that appears beside the selected figure. For this example, use the light brown color and rename it from 'Family 10' to 'Flesh'. Figure 2: Family colors dialog
4	Windows users should also click the 'A' tab and set the figure's object attributes to 'Positive'. Macintosh users don't need to do anything; objects are positive by default.
5	Duplicate the figure using the Duplicate command.
6	Click the colored tab by the figure to set a different family color. Call this one 'Jumpsuit'. You now have two copies of the figure, at exactly the same location but with different family colors.
7	Create a sphere. Shrink it until it is a little larger than the figure's head, and drag it into place so that it surrounds the figure's head and neck. You may want to stretch the sphere to make it fit more exactly, but make sure that no part of the figure's head protrudes from the sphere.
8	Assign the sphere a new family color, and call this one 'Cut'. In the Object Attributes editor, set the sphere's attributes to 'Negative'.
9	Duplicate the sphere, shrink it, and drag it until it covers one of the figure's hands. Adjust the size and shape of the sphere if necessary for a good fit.
10	Duplicate the second sphere and move the new copy to cover the figure's other hand. Figure 3: Figure and spheres
11	From the 'Select by Family Color' menu at the foot of the screen (a small brown/white/green-striped square), choose the 'Cut' family. All three spheres should now be selected.
12	Duplicate the selected spheres. You now have six spheres, and the three duplicated spheres are currently selected.
13	Click the colored tab to change the family color for the selected items. Choose another new color and call it 'Intersect'.
14	Click the 'A' tab to edit the object attributes for all three selected spheres. Set their attributes to 'Intersect'. At this point you have two figures, one labelled 'Flesh', the other labelled 'Jumpsuit'. You have three negative spheres labelled 'Cut', and three intersecting spheres labelled 'Intersect' (the names are not important, except to help you remember what does what). You are now ready to group the objects.
15	From the 'Select by Color' menu, choose 'Flesh'. Then, hold down the shift key and choose 'Intersect'. You should now have one figure and three spheres selected. Choose the Group Objects command from the Objects menu, or simply click the 'G' next to the selected objects. You now have a group made up of one figure and three spheres. Because the spheres are set to intersect, only those parts of the figure that lie within one of the spheres will be rendered. Figure 4: Grouped figure and spheres
16	Click the 'M' tab next to the selected group to assign a material to the group. The texture should be whatever texture you want to use as flesh.
17	Repeat step 15, but this time select 'Jumpsuit' and then 'Cut' to produce a group consisting of the clothed part of the body, with the flesh regions cut away.
18	Repeat step 16, assigning to the newly created group a material appropriate to the figure's jumpsuit.
19	Select both figure groups (using the marquee, or the 'Select by Color' menu, or by clicking the Group selector - the pair of linked toruses next to the 'Select by Color' menu) and group them to make sure that your figure will move as a unit in future.
20	Render the result. Figure 5: Rendered figure

As will be immediately clear, this technique is very far from perfect. For one thing, it offers only very limited possibilities for coloring figures. For another it is expensive in terms of memory (each different texture you want to use on the figure requires you to make another copy of the model: a figure with shoes, shirt, pants and skin of different colors would require four copies of the model). Another problem is that it is difficult to separate out parts that are very close to each other; a figure standing with hands on hips would be difficult to handle properly using this technique. Use of different primitives - blocks, cones, cylinders - may help in some cases.

Despite the limitations, this technique may prove useful if you are forced to use an old copy of Poser or work with other models which cannot be texture-mapped or broken down into subparts (this note has talked about Poser figures, but the same techniques will work with any other imported model). Even though the rendered results are poor, they may still provide a useful basis for post-editing in a graphics editor.