Is it possible to apply an HDR probe to a gropup of objects only. I would
like to apply it to everything in a scene except the plane I am using as a
floor.

Thanks,

Tim

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"Tim McMurdo" <jod### [at] wohrrcom> wrote:
> Is it possible to apply an HDR probe to a gropup of objects only. I would
> like to apply it to everything in a scene except the plane I am using as a
> floor.

POV, or MegaPOV? And why? :)

I don't know MegaPOV, but in regular POV 3.6, I think you could get this
effect (or pretty close) by doing it in two (or three) passes, and using
post-processing to composite one image with HDR and no floor & the other
with floor, but no HDR. The 3rd image is for the composition alpha mask.

I've just started playing with lightprobes, using HDRshop to convert probes
to spherical maps and then using PoseRay to extract light sources from the
image. I need to get some better probes (and play more with the ones I
have), but so far the results have been encouraging.

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PM 2Ring <nomail@nomail> wrote:
> I don't know MegaPOV, but in regular POV 3.6, I think you could get this

  POV-Ray 3.6 doesn't support HDRI. POV-Ray 3.7 does, though.

-- 
                                                          - Warp

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Warp <war### [at] tagpovrayorg> wrote:
> PM 2Ring <nomail@nomail> wrote:
> > I don't know MegaPOV, but in regular POV 3.6, I think you could get this
>
>   POV-Ray 3.6 doesn't support HDRI. POV-Ray 3.7 does, though.
>
> --
>                                                           - Warp


That will be great, Warp! But I'm having fun with my current system anyway.
I forgot to mention that I'm using Jaime's pseudo-HDRI macro, as well as
the light dome made by PoseRay. It's a little tedious putting the bits &
pieces together and doing the two-pass radiosity, but it does seem to work,
although I'm scared to use any area_light in the light dome lights. I've
also just begun to realize the extra realism and speed advantage in using
focal_blur and a little post-process smoothing, instead of antialiasing.

Of course, if POV could actually read an HDR file, it would be much better,
but I'm mostly using 48 bit .png files for my image_maps, and I'm hoping
POV can take full advantage of the 16 bits per channel, since it knows how
to create such files.

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"PM 2Ring" <nomail@nomail> wrote:
> POV, or MegaPOV? And why? :)


MegaPov...and the second is a very good question.

I am creating an pretty sparse image of some objects sitting on a white
plane. I want the reflections that an HDR image gives to the objects, but I
only want the shadows of the objects on the plane.

Using HDR applies colors to the white plane that I don't want.

Perhaps a better way would be to use a texture on the plane that would not
be affected by the HDR? Any hints?

Tim

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"Tim McMurdo" <jod### [at] wohrrcom> wrote:
> "PM 2Ring" <nomail@nomail> wrote:
> > POV, or MegaPOV? And why? :)
>
>
> MegaPov...and the second is a very good question.

As I mentioned, I don't know MegaPov or how it implements HDRI, so my help
will be limited.

> I am creating an pretty sparse image of some objects sitting on a white
> plane. I want the reflections that an HDR image gives to the objects, but I
> only want the shadows of the objects on the plane.
>
> Using HDR applies colors to the white plane that I don't want.

Is it only the colours that are a problem? I still think you will have to do
this in multiple passes, but in the first pass, just use a greyscale
lightprobe to get a colour-free white plane.

> Perhaps a better way would be to use a texture on the plane that would not
> be affected by the HDR? Any hints?

I've been wracking my tired brain for how to do it in regular Pov. In the
method I've been using, I guess I'd use lightgroups on some or all of the
lightdome light sources, and I suppose I'd use a big gray_threshold to kill
the colours caused by radiosity, since that won't affect the coloured
reflections you want on your main objects.

This problem reminds of those 'portal' type pics that Rune did a while back.
Maybe he has some hints, or maybe Christoff or Warp can illuminate us.

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