Hi folks,
I have a question regarding texture baking.
I have attached a simplified version of the scene I'm working on which simply exports a baked texture (constant purple) attached to a sphere (texture looks like purpleTexture).

When I re-apply this texture I am getting little black lines along the UV joins. (fig2)
Another poster asked a similar question and was advised to turn off all gaussian filters, which I'm pretty sure I have done.

I'm pretty sure the problem is somewhere in the mantra bakeTex node but I don't know mantra well enough to do much more than arbitrarily set values and hope the lines go away.

Any help would be appreciated.

I render with a filtering of minmax min, then in comp I expand by 1 pixel which gets rid of the lines . The lines are there due to the Alpha value of the pixels at the edges.
If you do a search over at odforce theres quite a few automated solutions to baking textures.

Rob

Thanks for the reply rob,
can you think of a way without having to do anything to the comp? I am trying to create a procedural tool.

Changing the pixel filter to minmax min had no effect without changing the comp (I guess that is to be expected).

I've done some searching and I can only find 2 posts to do with these lines (and a few outside houdini) and the consensus is ‘turn off filtering’ or pixel borders which I've tried to do.

Any chance you could fiddle about with my scene and get a non line-y sphere?

cheers

can you think of a way without having to do anything to the comp? I am trying to create a procedural tool.

No you need to adjust the texture in comp. You use COPs to alter the image and the whole process can be automated and done within Houdini.
The whole downside with baking is you're going to have to figure out how to bake the shader texture out and include the displacement and that means some re engineering of the shader. The next down side is the UVs must be laid out correctly and have no overlap and live in a zero to one space.

If you do a search and find my website you will find an alternative to baking out texture maps. In an example I use a Point cloud to look up occlusion and multiply it into a surface shader.
Lastly I really do feel in 2012 its pretty pointless baking out textures when you can have everything sit in an asset which lives on disk. Just recently I built a surface shader that will calculate occlusion on the fly what better than to be able to control the occlusion on a per object basis. Again on my site there is enough information to get you going.

Rob

I can see you're an expert and I'm sure your website is a hugely valuable resource (one of the old Houdini artists at my company told me about it when I joined) but my companies workflow includes other software and so, even if it is impossible, I'm interested in how to bake out something that could be used in maya/vray for example.

The UVing will most likely be done outside of Houdini and the digital asset I'm building projects textures onto geometry and blends the result. The tool is completely finished apart from these black lines and it feels like a bit of a cheat just to expand the texture in cops (this is what SESI recommended as well).

I'm happy to share the tool with you if you like. It is influenced by mario's texture projection shader. Could you maybe explain the filter that is causing these lines? I have been told it is not the case in other programs

I can see you're an expert and I'm sure your website is a hugely valuable resource (one of the old Houdini artists at my company told me about it when I joined) but my companies workflow includes other software and so, even if it is impossible, I'm interested in how to bake out something that could be used in maya/vray for example.

Baking a map for use in another application, that sounds like a minefield as who knows how the geometry will be effected or the subdivision handled.

The UVing will most likely be done outside of Houdini and the digital asset I'm building projects textures onto geometry and blends the result. The tool is completely finished apart from these black lines and it feels like a bit of a cheat just to expand the texture in cops (this is what SESI recommended as well).

Its not a cheat. There is no reason why the whole thing can not be automated.

I'm happy to share the tool with you if you like. It is influenced by mario's texture projection shader. Could you maybe explain the filter that is causing these lines? I have been told it is not the case in other programs

Sure post up your effort. I have not used other applications for baking so I cannot comment on how they work. Ive explained why you get the lines in the above posts. Feel free to PM me and let me know which “old ” Houdini user pointed out my site and where you are. I'm always interested to hear if people find my site useful and what interesting things they come up with.

Rob