HDRI map offset

[Nerox]

Hi,

I'm making my first steps on rendering in Houdini. I'm testing the HDRI indirect lighting workflow. I ran in to the problem that I'm not able to control the orientation of the HDRI map. According to the help, the map should be rotated by the light where the vexGi shader is linked to (or a specified null object).

The strange thing is that the HDRI map doesn't rotate along (or al all) with the light, or at least it isn's noticeable in the reflection/lighting. Though the reflection/light does change if I specify a null object, but again changing these rotate parameters don't seem to effect anything. Any idea's?

I've attached the scene file, you might need to redirect the map on the vexgi shader, I wasn't able to use the $HIP variable for this purpose.

[Nerox]

Oeps forgot to upload the attachment.

HDRI_offset.zip

[Nerox]

Oeps forgot to upload the attachment.

Always nice to find the answer on your own question, especially when there appears to be a $@$@^!! shelf button for it. ;-)

For those who are interested: Under lights and camera's on the shelf there's a button for Environment Light, which includes options under Area Light Options to specify a environment or area map. Yes the offset or rotation of the map works fine.

According to a reply of Jeff on the sesi forum:

It is best to use .rat files for texture maps (mipmap'ed images) in all cases. You need to use the command-line tool isixpack to create a proper rat environment map. isixpack takes either the traditional cross image or a series of 6 images that map to the standard 6 sides of a cube and builds a .rat image that contains six image planes each corresponding to front, right, back, etc... See the command line help for isixpack.

[houdineer]

I got the same question, and posted it on Houdini Apprentice Forum:

http://www.sidefx.com/index.php?option=com_forum&Itemid=172&page=viewtopic&t=18857&highlight=hdri+offset

But there isn't any suggestions yet.

Maybe changing the orientation of the HDRI map before importing it in Houdini is so far the only practical way I know.

Although it is not that intuitive to me....I still want the ability to adjust it directly in Houdini.....

It's so nice to see the same question been post on the forum, especially for the software that few people around me using it.

[Mzigaib]

If I use the environment light with the micropolygon my objects doesn't catch the reflections, it only works with PBR.

I can however, use a sphere with my hdr map textured to produce reflections on to my objects but I don't know how to align it with the environment or light template.

Is there a way to make refelctions work right with micropolygon render?

[Peter Quint]

On the environment map orientation I haven't tried it, but you may need to enable (on the render tab of the null object) output transform as render space.

On reflections you would need to use a reflective shader on all your reflective objects(such as the reflective material from the gallery) and use the same null object and environment map.

[Mzigaib]

Thank you very much!!!

It worked for the environment, the key was that transform option on the null, nice!!!

Now I am going to play a little to see if I don't have any more problems.

Again thanks for everyone.

[Mzigaib]

Hi, it's me again.

The problem now is not to rotate the environment or the light, the problem now is to align both since they're in separate spaces, It is very difficult to align the environment light with with you reflection environment, there's no intuitive way to do that.

What I am doing is to place a sphere with the hdr map textured on it and then I try to align it to my env light zero rotation and then try to rotate both with a single null, this null would orient my reflection environment and my env light together so they would be aligned, the problem is that theres no visual way to do that besides try and error with the render, it is very frustrating, I hope I could explain it right.

Anyone have any tip for that?