Trying to make HDR IBL... HALP
Oso3D
Posts: 14,915
Tearing my hair... well, mustache out.
Ok, so I've been using Paint.net and Gimp to create different 'exposures' of an image (using midpoint slider on Levels to push values brighter or lower). Creates what looks like over and underexposed images. Great!
Then I pipe it all into Picturenaut to create an HDR/EXR image with a higher dynamic range. It seems to work. Great!
I put it in Iray Environment map and... bupkis. Everything is just an almost perfectly even, colored, light.
I've tried skewing things toward brighter or dimmer exposures, still nothing.
Any tips?
(And yes, I've looked at lots of different pages)
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I'm trying to do this too, but have distractions at the moment.
It could be to do with the way the image is - is it just a straight image or a 360 180 panorama ?
Also what size is the image ? Maybe the size of the dome is not right for the image.
That's where I am at, so just further questions from me, sorry.
The information to get a proper HDRI isn't there in an ordinary .jpg picture. You would need to use the RAW file, equivqlent to a negative in film, and save a range of images using the exposure slider to set the different exposure values from very bright to nearly dark and then combine these into a 32 bit HDRI. The type of HDRI used for lighting is different from the HDR .jpg images that you see on the net.
I was making my panoramas using bracketing to make an HDR but there's still more to it as I hit a wall there. Also you can get tools to create an HDR from jpg.
a proper HDR isn't going to come from a JPG though. You can surely make LDR with JPG for use as IBL. But HDR is captured a particular way as Fishtales stated.
I don't know if it's as good an HDR as the ones I was making with my camera, I was just adding my thoughts on where I was at.
A true HDR requires a 32-bit file format.
Without specifics of what you're doing (pixel dimensions, aspect ratio, file export type, image content, etc.), it's hard to say what the problem is.
Supposedly if you start with a neutral image (like a jpg) and make a bunch of copies pushing effective 'exposure' up and down, you can then use Picturenaut (or similar) to layer it all into a true HDR.
But ... I can't seem to get it to work.
To start, if you are making 'exposures' and dumping them into Picturenaut, any format other than jpg is better...but uncompressed tif would be, probably, the best. Then you need more than a couple on each side...more like 7 down (until everything EXCEPT the 'sun' is nearly black) and 7 up (one below total 'whiteout'). These need to be in as uniform steps as possible. Then feed all of those into Picturenaut...
There is a list of tutorials which I posted here for making HDRI maps for using as lighting.
http://www.daz3d.com/forums/discussion/comment/899460/#Comment_899460
That program is supposed to be pretty good, and I'm sure you can get decent results using the method you mentioned. However the idea was really to use actual photos that used different exposures and not just photoshopped exposures. Or at least using the RAW image and making exposures from that. Using the exposure feature on a JPG isn't going to be quite the same, but I imagine it might provide decent results.
I know, but I don't even own a camera. The point is to see if I can take skydomes and images from Carrara and make something usably IBL from it without having to play games with spheres and spotlights.
If you don't care about the colors you can use less (and honestly this method you really is too brute force to worry about that) I managed to do a similar what your trying (and got some sharp shadows even) with just 3 images. Some I worked from a photo base (there are a lot of free ldr equirectangular images on the web) some I even painted everything. But after a while I realized that my good ole photoshop cs2 could work in 32 bits directly and I started just doing everything there.
But for making fake exposures and using picturenaut, the key for me was to use the exposure tools in my painting software and use tose as the exposure value for the images I input in picturenaut (generally by method was take my original image duplicate it on a second layer lower the exposure by say 5 and then erase the bits of the texture I wanted to be lighter and have the original image peep through (mainly the whites) Also I focused more on the lower exposures than the upper, fore one they are easier to understand you just make the bits you want sending out more light brighter on the lower exposures.
I hear ya. Just an FYI IBL and HDR are not synonymous. We have been using IBL without HDR for a long time. So you can use a regular image for IBL :) But I understand you want to make HDR, just pointing out IBL doesn't need to be HDR.
There are some advantages to HDR over regular images, but I've used regular images for IBL in lots of cases and they can be very useful too.
Yeah, the problem is Paint.net and GIMP don't have exposure stuff normally, so I'm trying to figure out how to do it properly from Levels. Which... is tricky.
This was my concern with just using exposure in a photo software. It uniformly dims/brighens the image and it's not quite right. So to get the best effect a bit of manipulation would be needed.
Another thing you have to remember is that .jpg is a lossy format meaning that a lot of the image is thrown away depending on how much it has been compressed. There will also be artifacts that can throw bright spots in the image where they aren't wanted.
I think I worked it out. The trick is that the underexposures are best WAAAAY underexposed. So I did something like 2x bright, 4x bright, 1/10 bright, 1/100 bright, 1/1000 bright. More or less.
And that's getting me the lighting I want, though the comments about artifacts, and also saturation, start rearing their head.
Edit: Also, for my purposes, I can solve most of these problems when generating backdrops by rendering them large and saving in a more raw format.
That's why I suggest working with tifs.
If your program lets you save as an .EXR that would be super awesome. You can use that as an HDR without making one. If not, you could actually render out the different exposures and save as something like tiff or png.
That's my intent. Still having trouble getting things quite right, but I've had at least one success, so it seems POSSIBLE.
You can do this in Vue with photoshop. Export in raw at varies exposures import into Photoshop properly and then save in a proper 32 bit format. By the way you can use a jpg for light but not anywhere as good as the real thing. You need a 2 to 1 format. eg. 8192 x 4096.
I believe you may be able to do this in Bryce as well. Vue and Bryce can do Panaromic pics. Bryce will export in a better format than jpg and there are loads of tuts on how to use Photoshop to make an HDR out of one pic.
Whilst on this subject (been watching too much British TV), is there any way to create a shader-mixed camera in D|S to take a 360x180 view? Apparently there is in Bryce
http://www.daz3d.com/bryce-7-pro-spherical-mapper
and I'm curious to see if something similar could be done in D|S. I assume not, or else we'd all be using such a thing.
Ron: Carrara can do panorama shots, and I own it. I might pick up Bryce some day. Vue, unless I'm missing something, is considerably outside my price range.
One big problem is that I don't have Photoshop and the other free stuff doesn't have a simple exposure function. (And, again, I don't have the money)
But really I CAN simulate exposures, the big problem has been figuring out which exposures I should be using. Which wasn't really obvious. (I've made two half-decent EXRs, but it took a bunch of tries to get the lighting to come out properly and mostly matching the backdrop.)
I don't think so. Reason is I needed a render like that. I had to export my scene to the standalone version of octane render to capture that type of image because the daz camera doesn't seem to support it. However If I am wrong I would love for someone to show me how to do it.
No, the default Studio cameras do not support it...and for that matter 99.9% of all 3Delight camera shaders out there won't do it, either. It was a feature recently added back into 3DL that had been missing since before version 6, I believe. And porting new shaders, ones that require the newest features of 3DL is not as easy as older ones (and I think those cameras are a version 12 feature, anyway....4.8 is still version 11).
Eh. Done with this for now.
I can get the lighting, but then the backdrop just looks... hazy and indistinct. Which is great if it works for what you are doing... here's an example (the lighting isn't very tight, but it works here).
It's WAY easier to simply work with skydomes and spotlights. For one thing, you have a lot more control over how the general sky vs. main light source affect the scene.
OK something important. HDR and IBL can be used as backdrops...however honestly no, no, no. At least most of the time IMO. It's a big challenge to get that to work right. IBL backdrops can be the secondary environment, but as a primary scene its going to be tough to get things like scaling right, and often colors.
But yes, it works there. Just a gentle reminder...
IBL are used as a source of light and reflections primarily. They help glue figures into an environment(cause of all those secondary colors that bleed into the scene that you would not have from regular lights). When using IBL, you typically have a primary light source (that is not the IBL) for casting shadows and illumnating things perfecty. However just using a regular light you will miss all the goodness of secondary coloring that IBL gives you.
Skydomes are OK, but frankly I found them more cumbersome than using HDR. Skydomes block light from the outside...so a pain. But I did have some good results with 3DL and uber environment when I was a big user. But I don't miss that workflow at all.
Can you use a general Sunlight and HDR with Iray? I find that combination works really well in a lot of cases. But most of the time I use HDR plus some mesh lights. Sometimes Sun with Mesh light helpers.
@timmons.william (can we just call you Bill, or Will, or seeing how you like to quote AA Milne -- Trespassers Will?)
Another thing to remember is that most graphics programs do gamma correction on the output -- they are set to gamma 2.2 (or thereabouts), standard for sRGB. The Environment dome wants linear (gamma 1.0) input. Other texture input nodes in D|S will force linear gamma for Iray (sometimes incorrectly, it seems, if the file is not color profile tagged), but I don't think the dome is one of them.
At least, the above has been my experience.
On geometry shell skydomes for pretty images: You can use the sectioning plane to lop off the top, letting in all the light you want from the Environment dome. I wrote it up here:
http://www.daz3d.com/forums/discussion/61704/tutorial-using-iray-with-3delight-skydomes
You could add an infinite light source to simulate the sun -- or I guess if this is in on Tau Ceti V, then the light from Tau Ceti. Remember to set the luminance pretty low -- that value is the light incident on the scene, measured per square centimeter (D|S default scene scale unit). On earth, mid-day sun has about 9.3 lumens per square centimeter. So a bright, blazing Tau Ceti might be around 12-15 lumens.
Of course if this is Talos IV, then you're on your own. (But at least you can have fun with the green woman of Orion.)