How can the walls of the ruin be weathered on the existing texture. I tried that with pasting pictures (just like the bushes) but that was not realistic enough.
The problem is that the wall texture (probably) is tiled and repeated over the whole model. Once you add “weathering”, you don’t want it to look obviously repetitive, but with a lot of variation: on some sides more, somewhere less, also not symmetrical (e.g. close to the ground more than a the top).
So the weathering would repeat itself in larger steps than the texture, which only can be achieved by creating a a super-large texture image.
This is typically called a “texture atlas”, where every face has its own region on the image file, and the texture is not really tiled anymore. (Search also for “texture baking”). The downside is that it would need to have an tremendous size and lose detail due to size limitations.
Computer games or some image renderers usually support multi-layered materials that are only combined for display.
But SketchUp supports only a single texture image.
- You can circumwent it by overlaying images (or textured faces) with a little offset in front of the wall. This PNG image would have varying transparency to show through the wall or cover it with plants or dirt.
- Another way is to duplicate the wall texture and edit it in an external image editor to add dirt. Instead of making a texture atlas containing the whoke ruin, you would just swap the texture on sime walls against the weathered texture.
- To make an image weathered, edit it in an image editor, overlay image layers of dirt/moss/ivy with an image mask. Use the eraser with a rough brush to randomly erase parts on the mask until the combined image looks good.Take care thta the final texture can still be tiled.
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Thanks for the detailed explanation. I decided to do the textures completely in Photoshop and produce as many variations as needed for the different walls.
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