When I was working on VW spot (I did the creature model in Houdini), the lighting TDs at RADIUM used HDRShop to create MEL scripts for creating lighting solutions based on HDR probe image. HDRShop has output for Houdini. It generates a script file, that I would just copy/paste into Texport. Lights and shaders are created automatically but the script.
I usually set about 32 lights in an array then delete the ones below the floor plane, resulting in scene that has 16-20 lights. HDRShop's LightGen plugin creates Python script that places the lights in spherical array.
So the scene has 16 lights all of which have different colors and intensities. There is one ASAD light shader with color fields that have expressions that take their color intensities from Light intensity value.
The lights also source a single v_blurshadow shader, with shadow blut set to range from 20-32.
The problem is that rendertime is very slow. Not at all conducive to production. It is much slower then using area lights with v_globalillumination shader and v_rayshadow.
I am wondering, how can I speed up the blurshadow shader.

Dave Rindner

The BlurShadow SHOP does very simple (read:bad) oversampling of raytraced shadows just by sending out hundereds of shadow rays and averaging them. This is not a good way to do what you want to do. You should rather render shadowmaps and then use the VEX RayShadow SHOP with an expression like `chs(“$OBJ/depthmap”)` in the filename field so that you can apply only one shader to all your lights. Now you can adjust your shadow softness using the depthmap blur parameter in the shader.

Also, if your scene is static (moving camera only), you can render the shadowmaps only once and save the expense of generating shadowmaps for every frame.

If you do it this way, it's much faster than true GI and definately MUCH faster than using many BlurShadow lights.

Make sense?
Jason

sorry to bump an old post but that's such a good solution, nice shadows and it's fast, thanks.

Sorry to bud in here…..

Im just learning how to use depthmaps in houdini and I dont want to deal with saving these depth mapths to my hd.

Is there there an expression to tell houdini just to generate depthmaps on the fly for each light using the shader so I dont need to worry about where these files are going and what is sourcing them…. etc. ?