I just down loaded a few hdri images. to use with baggins bill env sphere.

when I unpacked them they had a series of different extensions on them.

the files were for a milkway system.

3 jpegs and the following

milkyway.ibl  (1k)

milkway_light.hdr  (67k)

milkyway_small.hdr  (6.5M)

Curious as to what the differences are with these and to use them properly with

the sphere.

This is from the sIBL site, right?

While that can be used (as in better than nothing) it was made rather poorly. The HDR has no values above LDR maximum, which means it isn't HDR at all. The person who made it thinks that calling a file HDR makes it high dynamic range by virtue of the name and format alone. It doesn't. HDR files that have no values above 1.0 are not "high" - they are just files that could have been "high".

I would also have expected the file Milkyway_BG.jpg to be higher resolution, but it isn't.

You don't need the ibl file.

For the sphere, you can use either Milkyway_BG.jpg or Milkyway_small.hdr - you're going to get the same result, since they contain the same information. They are encoded differently but that makes no difference. Use either of these.

The file Milkyway_Light.hdr is not the same image as the others. It's got artifical splotches of light to make the scene lighting be brighter. It's no good for looking at and no good for reflections, either. Personally, I'd throw it away.

Quote -
I just down loaded a few hdri images. to use with baggins bill env sphere.
when I unpacked them they had a series of different extensions on them. the files were for a milkway system.

3 jpegs and the following
milkyway.ibl (1k)
milkway_light.hdr (67k)
milkyway_small.hdr (6.5M)

Curious as to what the differences are with these and to use them properly with the sphere.

The milkyway_small.hdr is just a photograph of the galaxy. You can stick it on your envsphere and have your reflective objects reflect stars and such.
The milkyway_light.hdr is to be used for lighting (not for reflection). It is just a smaller version of the milkyway_small with a lot of blur in it. You can use it for IBL lights in poser. Because this is used only for diffuse light, the image does not need to have a high resolution, the diffuse lighting calculation munges any details anyway. You could make this yourself by applying a gaussian blur (radius 200 or so) to the milkyway_small and then resizing it to the smaller size.
The milkyway.ibl is just a file describing the different images for a plugin they are distributing on the sibl site (not for poser, though), so you do not need to remember what to do with each image.

Quote -

This is from the sIBL site, right?

While that can be used (as in better than nothing) it was made rather poorly. The HDR has no values above LDR maximum, which means it isn't HDR at all. The person who made it thinks that calling a file HDR makes it high dynamic range by virtue of the name and format alone. It doesn't. HDR files that have no values above 1.0 are not "high" - they are just files that could have been "high".

This is not 100% correct. The important thing is the contrast of the image, not the level. The milkyway_small has pixel values between 0.0003 and 1.8 (found out by just picking some dark and bright pixels with the mouse) which gives a dynamic range of at least 1.8/0.0003 which is approximately a contrast of 6000:1. You cannot get this with a jpg image; but i have no idea if this value is correct for the real milkyway.

Oops - MG made me look again. I must have measured the wrong file before, because I now find that the HDR file has HDR data in it. My bad.

I blame Poser caching or my lack of coffee at the time - not sure which.

I just did a little normalizing. It would appear the JPG is more detailed, but range limited. However, increasing its amplitude by 6 gives about the same result as the HDR in terms of luminance, but it has more detail.

I say use the JPG.

Thanks bb and millighost 

Sorry about the short reply guys.

was out trying to write it on the bloodey new iphone4s. All thumbs when it comes to texting.

Its is from sIBL site. I was looking for some good night skies.

So using the .jpg I know I set my correction to 2.2 but as the .hdr from what I can tell so far does not not have the full range in it (unless I'm reading wrong) as to me 6.5 MB is about a quarter or less of all my other hdr files in size. Should I set my correction to 1. Which I do for my others. This I dont play around whith much. As reading many or your posts BB (actually miss way more than I get to read). So am not overly sure what effects would be caused by using say 1.1 or 1.3 etc. I could be way out in my thinking but if the file doesn't have the full range in it. Would adjusting the  gamma by .1 0r .2 compensate.  My apologies if this has been covered before.

Whne you refer to increasing the amplitude or luminance by 6, is that value in the HSV node?

Hi GeneralNutt

Yep in the HSV node I changed the value to 6.

rnning a test on it now.

I've always assumed that the *_BG files were meant to be used as backgroung images - hence the greater detail. That's the way I've used them in Vue anyway. I think that's what the sIBL plugin does in C4D, but it's been a while since I've seen it.