What's the deal with SketchUp?

I’m fairly new to Collada, but…

Many SketchUp models I import into my viewer seem wrong. All of the materials have a transparency color of 1,1,1,1 and transparency of 0, which means that they should not be visible at all.

As an example, I’ll refer to the AT&T Ball Park model:
http://sketchup.google.com/3dwarehouse/ … revstart=0

Consider the geometry node with ID=“mesh12-geometry” (line 1826).

The first triangle group renders most of the building in a simple “stucko” texture (via “material_3_1_8”). Without blending this is all that is visible. Removing it, then other textures can be seen. I assume that some type blending is necessary, but I’m not clear how to get that information out of the collada file. “material_3_1_8” defines transpareny as described above, but I don’t see how this is useful.

I have read other (older) posts that essentially say that SketchUp is not to spec. Is this still correct? I hope not, as SketchUp appears to be a huge source of free content. I am hoping that I am overlooking something in this file.

As a side note, I am using FCollada for parsing the dae file.

Thanks for any help.


You are correct. For applications that support <transparent> and <transparency> correctly, that model from SketchUp would be invisible.

Hi guys,

I’m the Product Manager for Google SketchUp, and I’ve had a look into this problem. It is true that earlier versions of SketchUp did produce COLLADA with the non-compliant transparency settings in them. In the current version of SketchUp (7.1) this problem has been fixed, and SketchUp does generate COLLADA with the right transparency settings.

It looks like we’ve still got some models in our 3D Warehouse that were generated with our older code– for example, the AT&T Ballpark model you referenced. We’re looking into that problem now to see if there’s anything that can be done to fix the files.

For now, you can process any non-compliant model through SketchUp 7.1 (free) to fix the transparency settings as needed.

Hope this helps-

It does indeed help thank you.

Is there a reasonable way to fix these inverted transparency files programmatically? I’ve tried flipping the transparency, but I’ve never had any luck. I’m using panda3d which uses FCollada.

If I recall the Sku problem, for each problem instance, either:

  1. change the value in the bogus <transparency> to 1 minus the value.

  2. add opaque attribute to <transparent> where <transparency> incorrectly equals zero. E.g. <transparent opaque=“A_ZERO”>

Note that (2) requires proper support of the feature.

The same problem seems to happen when importing Sketchup collada to Blender GE. The collada file imports fine to the scene but the textures do not render. Is there a simple work around for this? :roll: