Export vertex colours?

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#1

Hi,

I have a problem getting vertex colours to export in any format. I especially want to export using Collada .dae, but when it is opened in another editor (or even back into Blender) there is no Vertex colour information!!???

Is there some step I need to carry out before export?

Using blender versions 2.61

PS I’m asailmaker in UK and am trying to use this in order to use CFD to study sail design

Thanks,

Andrew

#2

this is just to Bump?

#3

Seriously, it doesnt seem to work for me no matter what I try, hasd anyone any idea how to export obj or dae vertex colours?

Thanks, A

#4

.obj format doesn’t support vertex colour full stop.

.dae should, I believe, support vertex colour but Collada support in Blender is poor to say the least.

What’s your target application? i.e. what formats does it support?

–
http://www.digital-air.co.uk/

#5

I know this doesn’t preserve the compactness of the VCol data, but as a fallback plan remember that you can easily Bake the colors to an image in Texture bake mode. Then it is only a matter of exporting the image and UV layout.

-rking

#6

Hi All,

Thanks for the reply,

I’m trying to export to Sketchup. I have some tubes (these are wind streamlines that are coloured by velocity). They show up and render just fine in Blender, but cannot get it to export to Sketchup with the coloured Vertex’s.

However, if I open the original file (X3d) in Meshlab, export .obj and re import into meshlab, it contains the coloured vertex’s correctly. However, if I import that same Obj into Blender, it does not see the colours.

The main point is I would like to export the vertex colours to a format that can be opened in Sketchup.

Thanks again in advance,

Andrew

#7

Rking,

Being a 2nd stage newbie, I have not done any UV mapping and I think the prospect of unwrapping (that was if I knew how to do it) several tubes and mapping it could be tricky. But I have no idea what Im talking about, so this could be wrong.

http://www.solosails.com/images/vertex.jpg

How do you map the painted vertex’s?

Cheers, A

#8

Ahhhh… well you can stop right there. Sketchup doesn’t support Vertex Colours. You’ll have to bake a texture.

–
http://www.digital-air.co.uk/

#9

Hmm, thanks for saving me some headbanging time.

OK, how or is it possible to Bake textures as the image above?

Cheers, A

#10

Hmm, that’s what i thought. I did take a look at the UV bake thing, but thought it would be impossible to unwrap all of those lines/tubes. a f=ing nightmare in fact.

Oh well, lets just hope they fix the dae export to start exporting vertex colours like it should.

However, as you say, there is no point anyway, because sketchup ignores it anyway.

Bummer.

Thanks for your help

Andrew

#11

Unwrapping those won’t be too hard. You’ll have to shop around through the Unwrap methods to find one that gives you a non-overlapping and fairly non-stretched result, but once you get to that point you can bake - it is not like you truly have to get the UV Map organized.

I know you probably don’t want to redo work, but I have a different approach for the whole thing I would like to throw out there in case the you end up needing a fallback plan. As it is, with the bake, you are going to have quite a bit of redundant data, and quite a bit of data, in the texture. You’ll have two tubes gradating from green to yellow in an almost identical way, but each will require its own pixels. What if you did this instead?

  • Create a single image gradient that has the major colors in the corners and blends amongst them. Actually, I wouldn’t create this - I am sure you could get something from a Google Image Search - or even a screenshot from an existing color pickers.
  • Make one tube, give it the classic tube seams (around the end circles plus one going lengthwise)
  • Unwrap (probably using u,u then changing the tool option from Angle-Based to Conformal so that it comes out straight.) My thinking is that you’ll want the lengthwise quads to be rather skinny so the difference in colors around the circumference is minimal. In fact I would take the very left verts and bring them backwards to the same positions as the right ones (again, to prevent a color difference at the lengthwise seam)
  • Adjust the location, rotation, and scale of this UV island. If your 3D Viewport is in Textured shading mode (Alt+z) you’ll see the result as you work.
  • Now duplicate the tube, and reposition it a bit in both the x,y,z space and the u,v space. Each tube should occupy similar, but slightly different, positions.
    Here it will probably help to put the UV/Image Editor into Island Select Mode so you can quickly adjust an entire tube with one selection click.

When you are done you will have all the complexity tucked away in the UV Map, and the gradients will be high-res even though the texture is not. I think my description may sound involved, but unless you run into problems somewhere I think you could recreate the entire spaghetti bowl in an hour or two.

-rking

#12

Wow, Im lost !

The main problem with the second idea is that the tubes are actual data, ie they represent calculated velocity of airflow, so they cannot be generic. But I will have a play with unwrapping. I have no idea how to do this, and when I have tried Blender has crashed due to the complexity of all those tubes I guess.

But thanks all for the input!

Cheers, A