HDRI - the misused term?

[voon]

I wonder: Why do people call texture environments "HDRI"? To my knowledge, HDRI means nothing else, than High Dynamic Range Image. Which means nothing more than a composite image, made up of different (usually 3?) images shot with different exposure settings to create an image showing all details, to approach what the human eye can do but a camera can not.

HDRI thus has nothing to do directly with a texture environment.

[glimpse]

You got the point here =) however HDR is comonly used to describe textured environment, because if You use it not only as a backplate, but as lighting element to light-up Your seen, probably You're going to for HDR (.hdr, .exr or at least .tiff) rather than LDR (.jpg, etc) so in this way HDR fits textured environment definition, just by 'defaul' without even saying You mean HighDynamic Range too will be used for lighting, 'cause it's obvious that You want that too. and for the record some even combine hdr from 12images..- then You can get really crisp shadows and wide range to play with exposure. Bad side of this - they weight a lot =)

[MDK]

If I'm not mistaken HDRI:s were created specifically for lighting in computer graphics initially. They do serve other purposes these days as well however.

People who use texture environments to light a scene use a HDRI most of the time since images with low dynamic range don't give good results. I haven't really noticed people misusing the term drastically. I usually say it like this: "the scene is light with only 1 HDRI". That is pretty accurate in my opinion. 3 is also a really low number of images if you want a quality HDRI.

I suppose people in someway misuse the term a bit. However people with experience in 3D computer graphics will have no problems understanding them.

[glimpse]

Exactly as MDK puts down - it depends where the term is used =) usually everyone understands what are You talkin about.

what is overused however is HDR photography - photographic style to push all the exposure into one LDR - that is missuesed or let's say too trendy & has little to no value..

Ben Horne (guy does serious stuff will analog medium =) talked 'bout this in one of his podcasts =)

[voon]

Aha .. yes, I have not seen this from the lighting point. Obviously, for lighting, you want more or less what is really there (at least to the human eye) and to mimick that, you need to use HDR with the limitations of a CCD/CMOS chip.

[Olitech]

And then of course, there is the term IBL: Image Based Lighting. Which, of course, uses HDR images. =D

I remember attending the Siggraph Conference where Paul Debevec shared his HDR technology for the first time. Images to light 3D geometry!!?? Whaaaaat???

Needless to say, everyone's minds were blown! All you could hear were gasps and brain cells exploding.

best,
O

[Rob49152]

I think the main reason for HDRI (or IBL) is that it captures the exact color temperatures for any given light. When the HDRI is created using any one of the panoramic formats it also gives very accurate visualization of all the lights and their source locations. That's why you'll see people taking photos of the mirror balls for any VFX shot. It makes for a much easier time when compositing elements together.

A good HDRI uses much more than just 3 f-stops for creating an image. I'd say the more the better because that way you get good information on the lighting in the shadows and dark areas.

I also hate the look of the popular HDR photography. It makes the photo look fake and overly saturated in unnatural ways.

[roeland]

The difficult part of HDR photography is tonemapping the final image. You have to display it on a regular screen or a print with much lower dynamic range than the image. And it is difficult to reduce the dynamic range of the image while still keep the impression of contrast between the dark and bright parts of the image.

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Roeland