I’ve put up a thing about using Megascans with Renderman. A lot of the info in there is transferrable to other aspects of look-development.
Videos are also available on Youtube.
Playing around with PxrSeExpr
This got started from a question on the Renderman forums about the difference between ST and UV. Renderman uses UV and ST to differiate between “implicit” and “explicit” texture coordinates. Implicit is automatically defined by the geometric shape and explicit is manually defined by the user.
With polygons and subdivision geometry, Renderman uses ST coordinates for texture mapping (it converts Maya UVs to Renderman STs behind the scenes). But it also automatically assigns UV coordinates to each face on the geometry, you might ask why would you need this?
For fun and profit!
Heat Map
Useful if you ever want to better visualize data images.
Basic idea is to put the data in the red channel, normalize it between zero and one, then make sure the green and blue channel are both set to one and convert the colourspace from HSV to Linear.
Blackpoint and Whitepoint are set to the minimum and maximum samples from the render. Gain is set to 0.666667 so that the range is mapped from Red to Blue, rather than Red through to Red.
HyperLogGamma
Nuke expression reminder to self. Linear to HyperLogGamma and back again.
r = current channel (r, g, b) a1 = 0.17883277 b1 = 0.28466892 c1 = 0.55991073
To HLG
r > 1 ? a1 * log ((r) - b1) + c1 : 0.5 * sqrt(r
From HLG
r > 0.5 ? exp( (r - c1) / a1) + b1 : 4 * pow(r,2)
Linux for CG – “easily goto directories, even if they don’t exist yet”
Quick little tidbit. This tests to see if a specific directory exists, if it does it goes to that directory, otherwise it creates the directory and then goes to it.
alias makeshot 'test -d /prj/$PROJECT/$SHOT/ && cd /prj/$PROJECT/$SHOT || mkdir -p /prj/$PROJECT/$SHOT; cd /prj/$PROJECT/$SHOT'
The first part ‘test -d’ checks if the directory exists, the command after && runs what happens if that check is true, the command after || runs if the check is false.
Renderman Denoising
A few little tips and tricks for Denoising stuff in Renderman…
Most of this comes from here… https://renderman.pixar.com/resources/current/RenderMan/risDenoise.html, you’ll need to make sure your environment variables are set correct to do this in the shell.
Note: This is using Windows, a lot of it is similar to Linux/Mac, there might be some syntax differences.
For all examples, we have a directory which contains the following image sequences…
RIS_denoised_variance.####.exr (the main render pass) RIS_denoised_variance_directdiffuse1.####.exr (key light diffuse) RIS_denoised_variance_directdiffuse2.####.exr (environment light diffuse) RIS_denoised_variance_directspecular1.####.exr (key light specular) RIS_denoised_variance_directspecular2.####.exr (environment light specular)
To denoise several frames (0001-0007) of the beauty render using single-frame denoising. Include the { } brackets around the frame numbers, wildcards * don’t seem to work for me in Windows.
denoise RIS_denoised_variance.{0001,0002,0003,0004,0005,0006,0007}.exr
To denoise the same seven frames (0001-0003) using cross-frame denoising.
denoise --crossframe -v variance RIS_denoised_variance.{0001,0002,0003,0004,0005,0006,0007}.exr
To denoise the AOVs as well, only on three frames this time…
denoise --override filterLayersIndependently true -- RIS_denoised_variance.{0001,0002,0003}.exr RIS_denoised_variance_directdiffuse1.{0001,0002,0003}.exr RIS_denoised_variance_directdiffuse2.{0001,0002,0003}.exr RIS_denoised_variance_directspecular1.{0001,0002,0003}.exr RIS_denoised_variance_directspecular2.{0001,0002,0003}.exr
Renderman Things
I’ve been doing some Renderman things.
Linear to sRGB
Putting this here for reference, I had this written down as a function to convert from linear light into srgb.
// encode from linear light to sRGB luma
float sRGB_encode_f(float F)
{
float lin;
if(F <= 0.00304)
lin = F*12.92;
else
lin = (1.055 * pow(F, (1.0/2.4)) - 0.055);
return lin;
}
Custom Image Sequences in Nuke
Quick tip. To use custom frame sequences in Nuke…
Step one. Enter the frames you want to use, with an image per line.
Step two. Enter in the following TCL expression.
[lindex [knob sequence] [expr [frame]-1]]
Done.
VFX and Animation by some Numbers
If you’ve ever wondered how big the VFX and Animation industry is – this might give you some idea – and I have no idea how accurate this is.
I searched Linkedin for the most visible studios in the industry and recorded down how many employees were listed for each studio. Keep in mind a few things…
- This only includes employees who are on Linkedin.
- Relies on people entering the correct name of their employer and/or keeping their information up-to-date.
- If your wondering why Lucasfilm is on there – lot’s of ILM people put it down as their employer (it technically is I guess). Impossible to know how much of those are ILM people versus other Lucas companies.
