.hdr Instead Of .rat???

[Overload]

Hey All,

Is there a way to use .hdr images that are NOT in the 3x4 format as the help manual suggests for Image Based Lighting?? I tried the conversion to .rat and it works fine with the format they say (probe I think they call it), but with a regular .hdr it throws an error about it not being in the 3x4 block . We have a ton of hdri dvds at our studio that we use with 3dmax everyday, but they are not in that "probe" format. Here is the pagelink from help where it talks about it if this doesn't make sense. Thanks a bunch

hdox://houdini/content/base/tutorials/fm_09_guide_lighting_1013795.xml

Anthony

[edward]

I think you can convert them using HDRShop.

[Allegro]

How would one go about plugging in a .hdr file?

In Maya, it's pretty simple to set up some hdr lighting... simply convert the hdr to a longitudinal map, put it on a surface shader, and then add the texture to a sphere. Rotate the sphere around to get the image lighting the scene the way you want, then render with final gather turned on.

With Houdini, I attempted to follow the help card. I have no idea what the environment is doing though when I attach it to a light... I'm trying to do a sunset type scene, and I want the sun in a certain location, but I have no idea how to figure out where the sun will be.

-I start with a cross shaped hdr

-I convert it to rat with the command line, isixpack skycross.hdr skycross.rat

-I plug it into the light... and... it seems really not like what I expected it to be

so... I open up the rat itself, and it's a reeally bright red, and it's only one square of the cross... so... I attempt it at various other sizes incase it's because my hdr was too big or something... doesn't help

-so then I just plug the hdr cross itself in... and it works better, but it looks like all the black from around the edges is appearing as part of the light map or something... there's black spots all over my models... Is this a problem with my image? Or does this have to do witht he quality settings of my render?

-so then I read that it works with probes, so I convert my cross to probe... command line will not convert it to a rat... so I plug it straight in... looks almost identical to the above test with the hdr cross.

I need some big time help on this! I'm trying to render something out by thursday. I may end up have to resort to spotlights if I can't get this working.

[edward]

The part 2 in the help assumes that you're working with the file from part 1:

hdox://houdini/content/base/tutorials/fm_09_guide_lighting_1013748.html

You're supposed to put the .rat file in the Environment Map parameter of the v_gilight VEX Global Illumination VOP. Try using the sample file from part 1.

[sibarrick]

The part 2 in the help assumes that you're working with the file from part 1:

hdox://houdini/content/base/tutorials/fm_09_guide_lighting_1013748.html

You're supposed to put the .rat file in the Environment Map parameter of the v_gilight VEX Global Illumination VOP. Try using the sample file from part 1.

Yeah the down side to this being you don't get any visual feedback as to how the environment map is oriented relative to the scene. Same problem with environment reflection maps. I always end up mapping onto a sphere and setting the sphere to be a phantom, of course that won't work in this case, but it needs something like this to make it easy.

[Allegro]

Yeah the down side to this being you don't get any visual feedback as to how the environment map is oriented relative to the scene. Same problem with environment reflection maps. I always end up mapping onto a sphere and setting the sphere to be a phantom, of course that won't work in this case, but it needs something like this to make it easy.

Thanks, I found this thread: http://forums.odforce.net/index.php?showtopic=2988&st=12 after I had posted here, and did end up going with a sphere and setting it to phantom. The whole notion of attaching a map to a light... seems ok I guess... but it's not intuitive for arranging it so that your hdr lighting matches the angle that you want.

[deecue]

and it's only one square of the cross...

this is because the rat environment maps made by isixpack are cubic deep raster files.. your other 5 sides of the cube are sitting in planes beneath that one and are still being accessed.

Yeah the down side to this being you don't get any visual feedback as to how the environment map is oriented relative to the scene.

agreed. i would love to see a visualization option on the light itself.. because i've even mapped it to a sphere before and had to play around with the rotational offset to see if i could get it to line up with what i thought was being generated in the rendered image.. the other thing that's not clear is what exactly the v_gilight shader supports for maps.. according to the odwiki, mantra supports cross, cubic, and latlong maps and if it's an hdr, it assumes it to be in cross format. but the H docs don't say anything about this. the IBL tut just says to use cross maps and convert them.. this is unfortunate for a place that has a library of only latlong hdr's. it seems like when i plug the latlong hdr map into the env param, it works just fine.. but there's no way to be sure of the orientation without guess work..

now i could be completely missing something, so please tell me if i am.. but it seems like things could be a whole lot clearer in the docs.

[beeemtee]

it's just an idea, but you can give it a try: make a sphere with VEX Super Material and use your environment map as the reflection map. maybe that could give you a much better and faster feedback about how your map is oriented in the scene.

if it doesn't make sence, please ignore me.

cheers

bmt

[Overload]

Well lately I haven't had many issues converting to the cross format (its very simple inside hdr shop). But the fact that there is no visual feedback makes it kind of difficult. For the time being I just map to a sphere and line up that way, since all I really want from the HDRI is the reflections not so much lighting my scene or objects. I still struggle with getting soft lighting in Houdini though without the use of GI, which just takes forever...

Edited April 9, 2007 by Overload

[deecue]

(its very simple inside hdr shop)

true.. but i don't think we have a commercial liscense here which is kind of a bummer.. plus that's double the storage to go ahead and convert everything when it should be easy enough to just use a latlong envmap.

I still struggle with getting soft lighting in Houdini though without the use of GI, which just takes forever...

have you looked at going the deep shad route? even though AO is becoming pretty standard, you can still approach it with a traditional light rig and deep shadows to get that softer look you're after...

[Overload]

true.. but i don't think we have a commercial liscense here which is kind of a bummer.. plus that's double the storage to go ahead and convert everything when it should be easy enough to just use a latlong envmap.

have you looked at going the deep shad route? even though AO is becoming pretty standard, you can still approach it with a traditional light rig and deep shadows to get that softer look you're after...

I haven't tried deep shadows yet (ashamed to say), but I spent most the day yesterday making a new lightset using mainly area lights, which make for very soft lighting. I may try deep shadows off one of those as opposed to doing AO or GI. Is there a way to use latlong envmaps instead of the cross format?? We use them in 3dmax everyday and have tons of DVDs so converting those is a major pain. Thanks man