HDRI - lighting

[strahlentherapeut]

Hi,

somebody knows for sure why some hdri maps are very small, in which other maps have a very big size. For example hdris from openfootage are very big, hdris from sibl archive are very small. And why the .ibl file has only 1 KB?

thank you

[SATtva]

somebody knows for sure why some hdri maps are very small, in which other maps have a very big size.

The same reasons why some renders are small while others are quite large.

And why the .ibl file has only 1 KB?

This file contains only metadata regarding sun positioning, etc.

[strahlentherapeut]

Hi,

I dont understand the context
There must be a plausible reason ( plausible for non developer ) why the hdr files from openfootage ( for example) are 15- 20 times larger than other hdri files? Are the larger files better, nicer more accurate or better for rendering? My RAM also have a say

st

[Abel]

The most important factor is resolution; a file of 2000x1000 pixels will be four times as big as one that is 1000x500 pixels. Apart from that, the content within an .exr file can be compressed, so the file size also depends on the compression algorithm that is used and on the contents of the image: a clean blue sky should result in a much smaller file than a noisy image with all kinds of unpredictable colours.

[sprocket]

Are the larger files better, nicer more accurate or better for rendering? My RAM also have a say

st

If you have a scene where you can see the background, either directly or through reflection, then you would want a higher res so it looks pretty. on the other hand if your using a hdri for a studio setup, then the higher resolution wouldnt be needed.

[strahlentherapeut]

O. k.,

thank you guys . I need the HDRIs in the moment primary for lighting. When I dont have 360 panorama HDRIs, I must more exactly setup the HDRI for lighting the scene? I see that right?
Or HDRI in latlong mode are always 360 degree?

[zeealpal]

http://zbyg.deviantart.com/art/HDRi-Pack-1-97402522
http://zbyg.deviantart.com/art/HDRi-Pack-2-103458406
http://zbyg.deviantart.com/art/HDRi-Pack-3-112847728

This user has a number of small lighting HDRi's for free, might find them helpful

[Abel]

When I dont have 360 panorama HDRIs, I must more exactly setup the HDRI for lighting the scene? I see that right?
Or HDRI in latlong mode are always 360 degree?

Most of the latlong HDRI images do cover 360 degrees, in particular when their image ratio is 1:2. When they don't cover that range it will be quite tricky to set them up properly so I'd suggest sticking to the 360 degree ones unless you have a very good reason not to.

[strahlentherapeut]

O. k.,

thank you.


Edit: The illustrations on the HDRIs are not important, when I use it for lightning only? I mean if they do not disturb for neutral lightning. And must I rotate this pics to a specific way, when they are not 360 degree HDRIs? Thank you for your help. And which setting I need ( latlong, spherical etc.)?

[SATtva]

http://www.luxrender.net/wiki/Environment_map