KML 2.2 introduced ResourceMap (textures.txt is deprecated)

Because COLLADA (.dae) files don't contain textures, but instead simply reference them on the filesystem, it is sometimes necessary to re-map these references to their correct locations. ResourceMap allows for exactly that.

For example, if the model file references "../files/foo.jpg" but the actual texture is located at "textures/foo.jpg" (relative to the .dae file), you can use a ResourceMap with "../files/foo.jpg" as the sourceHref and "textures/foo.jpg" as the targetHref.

Remember, the targetHref references are relative to the .dae, not the KML.