I have a very basic understanding of 3d in general, sorry.. Could someone elucidate the process of modelling in Houdini and texturing using photoshop for me please, specifically the steps required to get my objects out of Houdini and into PS CS4, and back again,….Do I export obj files? How do I add different channels like bump, specular etc…?

If this is too basic for this forum a push in the right direction where I can ground myself in the fundamentals would be greatly appreciated
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thanks

If this is too basic for this forum a push in the right direction where I can ground myself in the fundamentals would be greatly appreciated

I do not even know if it is possible in CS4 .I would suggest you first try and download any .obj object from the internet and see if CS4 imports .obj files .
That will then answer your question.

For beginners, getting started information look at the apprentice section on this website.There are lots of videos and of course reading the help for the application is always a good start.


Rob

Thanks Rob, it is possible, but when I load a texture onto say the diffuse layer of an obj I exported from Houdini, it becomes weirdly stretched in some places, yet correct i others.. I guess I just need to understand UVs a lot better, and how to prepare them in houdini before export… is there a simple one node parameter that just sorts them all out correctly and automatically?

I did try searching the archives for an answer but couldn't find the right info.. i'll start again focusing on UVs

cheers,
joe

Look at the video tutorials on this site “ basic UVing ”. Then when you get stuck ask but be sure to look at the help for each node. There are often example files you can load. In the example files middle mouse button ( MMB) on the node to read the comments on what the node is doing

rob

thats exactly wat I needed Rob… thanks!

Hi, since I just got done working through some of the same things, maybe my experience can be of help.
Houdini has a couple of UV nodes that might be helpful, or might not, depending on what you want to do. There's the UVUnwrap node which will unwrap everything you've selected and make a best guess as to how things should fit. That can be pretty useful, depending on the shape.

There's UVProject and UVTexture which can project a shape onto a UV surface. Useful if you've got a flat, or relatively flat surface you're UVing.

For organic shapes there's UVPelt, which is what the sidefx UV video covers. This takes some time to get used to, but it does a good job, assuming an organic shape, like a body, or head, or something like that.

For more complicated hard surface objects, such as a car or jet, or spaceship, things get a little more complicated and I found Houdini's current UV toolset lacking. I ultimately chose to use Modo to unwrap things and then just brought that back in. That's pretty easy to do, you can export your geometry from some point in your SOP network, let's call it “A”, as an obj file. Bring this into your third party app. UV edit to your heart's desire, then save out the result as a *new* obj file. In Houdini create a new file node in your geometry container, and load up the obj with UVs, let's call this “B”. So at this point we have 2 unconnected networks, “A”, and “B”, with “B” containing a set of UV coords. You can use the AttribCopy (or AttribTransfer) to copy from B to A and then from that point in your A network you keep on modeling, as the UV coords will be copied or transferred over.

Make sure to “test” the UVs by adding a material with some sort of checkboard pattern (there's one just for this in the Material Library), and then examine the model to see if there's distortion in the pattern. You want to try and keep the flow regular and avoid weird scaling issues, since that will end up distorting your texture.

Once you've got all this setup and you're happy with your UV layout, you can start painting in PS. You can export your UVs as a transparent image by right clicking on a SOP node (anywhere after the UV's have been added), and click the Save UV menu item (it's something like that). This will prompt you for a filename, and UV size - make sure you match this with what you're going to work with in PS, otherwise the scaling makes it look nasty. I usually use PNG for a format, Houdini will make it transparent with a white wireframe of all you UV's to that point.

You can bring that into photoshop, add it as a layer and start creating your textures.

There's a number of different materials that have individual channels for diffuse color, spec, and displacement. The Basic Surface and Basic Displacement both support diff, spec, and disp texture maps. Ditto for some of the others.

If you want to make something a little more advanced you can create a custom shader and use the Vex Super Material as a starting point. This has support for spec, diff, ambient, and many others, all controlled via texture maps. The Vex Layered Material allows you to layer these things, something a little bit like how things work in Modo.

Funny, I was reading through your jet thread, and ‘sort of’ getting it all.. but this has cleared up most all my outstanding questions… thanks for taking the time to explain it all.

No problem, if you run into other problems feel free to ask. I'm glad someone else found something useful in all my head banging