haikalle

Vector Displacement

33 posts in this topic

I already got the file. thanks! Now it's working. There is so many options that you can go wrong with. It took like 4 hours until I noticed that I have scaled my model and that's why displacement map looked all wrong.

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Hello

I'm not so au fait with all this vector map v normal map stuff (kudos to you), but as you're kinda new to Houdini I wonder if you've seen the GLSL tangent / object space normal map materials?

There is an example file from the help card here http://www.sidefx.com/docs/houdini9.5/node...angentnormalmap and here http://www.sidefx.com/docs/houdini9.5/node.../ogl2_normalmap

There also exists another example file with a vopnet which is hidden away on the Exchange, here http://www.sidefx.com/exchange/info.php?fi...p;versionid=562

The tangetspace example uses an inline vop to include a vop function which isn't exposed as a vop node, so you might have missed it if you weren't looking outside vop land. Just though you might be interested to know about it if you didn't already... if you even find it useful, that is.

Also, if you ever encounter any extreme displacements sometimes applying the vm_redice property to your material or object can help mitigate issues - http://www.sidefx.com/docs/houdini9.5/props/mantra9_1

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Thanks so much for this information. It's very helpful. I will look into this.

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Hi folks

This is an interesting thread. I'm a houdini user myself!

What would be the workflow in 3d coat's voxel sculpt mode with regards to exporting the vector displacement to be used in Houdini?

regards

Erik

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Hey people

Ive been doing some research into vector displacement with houdini, and was messing with the shader you guys have been working on. Looks like it has some problems with negative displacements. Theres a more detailed explanation here as well as a screenshot of the problem.

Anyone know why this would be happening? It be great to solve this as I have a vector displacement baker in works using Houdini and they would go great with each other. I cant quite see where the problems lies, the shader looks correct to me.

http://www.sidefx.com/index.php?option=com...pic&t=15077

Cheers

Nick

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Try opening up the exr in photoshop and adjusting the exposure (add a stop or two) to make sure negative values are actually there (they're normally displayed as black since the're stored as "blacker than black"). If you saved with black (not normalized), they should be there. If not, it's a bug with 3d coat not saving negative floating point numbers in exrs and Andrew would have to address that. Alternatively, you could save as a float point tiff, open in PS and save as EXR (not sure if houdini supports float point tiffs). Again, you'll have to adjust exposure to make sure the negative values are actually being saved.

The EXR file format itself supports full dynamic range (signed float point numbers with no restrictions) so it's perfect for displacements.

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You can also use Houdini's viewer "Mplay" which has an Adapt Range button and easy single channel viewing, see image for quick help.

Houdini should support floating point TIFF just fine, though to be honest I usually use EXR.

Last tidbit before I sleep: When rendering in Houdini, convert your images to RAT format which is Houdini's native texture format. Houdini can use almost anything for a texture, but RAT will be fastest with least RAM used. You can use Mplay to save out an image to RAT, or the standalone tool "icp" (shell on Linux, terminal on OSX, Houdini Command thingy on Windows, sorry I don't use Windows much I forget the menu entry name).

FYI this viewer is available from the free version of Houdini (Apprentice) for Windows OSX and Linux in case people want a really nice image (and flipbook) viewer.

Cheers,

Peter B

post-2142-12566244187166_thumb.jpg

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This topic was on the top of the forum, so I decided to make one more try to fix this thing. I don't know what I did but now it seems that both positive and negative depth works.

See the picture. Psyborgue, if you are out there, maybe you can check the houdini file and see if there something to fix. I added Fit Range node just after texture node and that seems

to work nicely. I will make a small tutorial soon how to make this work in 3d-coat and houdini.

post-1165-12566377355032_thumb.png

testt.zip

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