Shadow Problems

[Jon]

I am currently working on a project modelling and animating the building of a LEGO Technics model using Houdini. I have got to the stage of rendering and am currently fine tuning a few things in order to get a final render I'm happy with.

I have set up one of the lights in the scene to cast shadows, and have created a VEX shadow shader to use as that light's 'SHOP Shadow'. I currently have it set to render Fast Shadows. However, rendering a shadow pass is very slow, getting on for 20 minutes a frame. The scene itself renders quite a bit quicker, as I have split it into a couple of sections, which I then Z-comp together afterwards.

I have been doing some tests with z-depth or deep shadows, as I understand that this should improve the render performance a bit, but have been running into a few problems. The screenshot below shows part of the model, which when I render with z-depth shadows, I seem to get what looks like the Houdini logo cast as a shadow.

Does this mean z-depth shadows are not available in Apprentice, or am I doing something wrong? I have attached a cut down version of my hipnc file, which should demonstrate the problem.

Any suggestion on where I might be going wrong, or advice on how to improve the render performance of the shadow pass would be very much appreciated.

cheers,

Jonshadow.hipnc

[Jens]

I recently noticed the Houdini watermark on *.rat files too. I think there is no way to avoid that with the apprentice edition. Unfortunally compared to the picnc format the watermark in rat files won't be removed if used internally.

Did you plan to composite all z-depth maps and rerender the sequences later on with that layered z-depth mask ?

[Jason]

I recently noticed the Houdini watermark on *.rat files too. I think there is no way to avoid that with the apprentice edition. Unfortunally compared to the picnc format the watermark in rat files won't be removed if used internally.

Did you plan to composite all z-depth maps and rerender the sequences later on with that layered z-depth mask ?

A good and quick solution for SESI for this type of problem would be to just make the logo's values be really bright - like 100000 or something, which kinda guarantees that the shadow would be way behind the typical scene size Kinda screws up the Mplay autofit functionality though:)

[Jens]

A good and quick solution for SESI for this type of problem would be to just make the logo's values be really bright - like 100000 or something, which kinda guarantees that the shadow would be way behind the typical scene size Kinda screws up the Mplay autofit functionality though:)

Arg no ... bad enough to have the logo in any hdri reflection / lightening map. At least when using this isixconvert command and turning the maps into a rat file suited for the enviromental VOP. If you'd turn up the brightness *cough*.

[Jordan]

Hi, Jon.

I've looked at your file. I changed the z-depth shadow to deep shadow instead.

Here is an attached image.

When i increase the z-depth map resolution from 512x512 to 1024x1024 i got this "phantom object" casting shadow. Hell know where is it from?? i will have a look at it carefully when i m free, really interested to know the problem. I may get it one day.. who knows? and yea... is the watermark as jens and jason concerned.

I found this information somewhere else. I've forgotten the link. If someone know please make a credit to the author.

Shadow Map Memory Use.

128x128 0.06mb

256x256 0.25mb

512x512 1mb

1024x1024 4mb

2048x2048 16mb

4096x4096 64mb

once you are happy with your shadow-look, please turn off automatic generate z-depth map to render. Otherwise, it would generate z-depth map each frame that you render.

Here is the file with a little changes i made from your originally posted hipnc files.

shadow_new.hipnc

[Jason]

When i increase the z-depth map resolution from 512x512 to 1024x1024 i got this "phantom object" casting shadow. Hell know where is it from??

I believe this must be from Apprentice having a maximum render resolution of 768x576 (PAL) and any image area outside this being blank, maybe?

So many people seem to fall contravene Apprentice limitations that it seems like Mantra and Houdini should spew copious warning messages to that fact or people will just get frustrated and consider Houdini as buggy or hard to use.

[Jordan]

I believe this must be from Apprentice having a maximum render resolution of 768x576 (PAL) and any image area outside this being blank, maybe?

yes, it is. after i read your reply, i turned on COP to double check the z-depth map, oh yea.. i was set it to 1024x1024. Look carefully the z-depth map has been rendered is 768x576 it is simply because of the apprentice version restrict the render size. So the out of coverage area will be read as shadow area? good to know that.

here is the attached screenshot.

[Jon]

Hi,

Sorry I've been a few days replying to this, but i've been a bit busy these last few days trying to tie up the last bits and pieces with this animation. Thanks very much for your help, the deep shadows worked pretty well, even with the limited resolution, so I have decided to work with those. I'd spent a few days trying to figure out the best approach, so your suggestions were very helpfull!

thanks again,

Jon

[stu]

Very nice!