Transform of skydome jpgs to iRay-Dome hdrs?
AndyS
Posts: 1,434
Hi,
for most of my outdoor scenes I used a skydome with several different pictures (.jpg) of the sky.
As I read, iRay Dome needs special iHRD files to evaluate the position and intensity of the sun and the diffuse lighting situation shown in the background sky picture.
Now my question:
How can I transfer my sky pics into that special .hdr format?
What tool to use and what steps have to be performed?
Yours
Andy
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No, there is no easy way to transform a low dynamic range jpeg image into a useful high dynamic range one. Yes there are several tools that can make an attempt, by layering several copies that are adjusted several 'stops' up/down, but the best that happens is a midrange image that may/may not produce useful light or shadows. An hdr image starts out with a massive amount of data. The jpg is a small portion of that data. It's easy to make a tonemapped jpg from an hdr, but nearly impossible to recreate that 'trimmed'/discarded data to get the hdr 'back'.
Yea, I know.
It wouldn't be any problem for me to change the contrast of my pics to a much higher value. But what is the file format of an .hdr like?
My pics have 16384 x 8192 pix. So enough resolution for big size renders.
I tried but didn't succeed. The file format (jpg / png) was not recognized as HDRi by iRay.
Here's some info on the exr format...
http://en.wikipedia.org/wiki/OpenEXR
Changing contrast isn't going to give the full range that an actual hdr has. The exposure values are set when the pictures are taken...and then combined, at the raw data level, to produce an image that preserves all the information of each exposure. Just combining several images of shifted contrast is only going to 'restore' a portion of that information. And whether or not that is enough is another question...
Those hires jpgs are great for backdrops, but not for any kind of lighting.
Here's a page on how to do it in Photoshop...just be warned, the results from 'fake' bracketed (contrast adjusted jpgs) won't be as good as the real thing.
http://www.dummies.com/how-to/content/how-to-create-hdr-images-in-photoshop.html
Yes,
there are some on deviantart.
--> http://zbyg.deviantart.com/art/20-HDRI-Images-109988135
But they're not really working with iRay. At least I don't know how to set the intensity parameters. Either I get enough envi light but a way too light dome or a good dome but almost no envi light. I tried the ressource 2.
Ah wait.
The hint in the www.dummies ... article is interesting.
I was ever thinking about to switch to Photoshop for my usual photo work. Up to now I used a more simple product. But this is not able to generate hdr.
That's the typical problem with ones constructed from low dynamic range images...
One of the dirty little secrets of HDRIs is that even in the case of commercial ones you rarely find more the 8/9 stops of luminance variance. Finding properly done (12/14+ stops) ones is not easy at all.
Quite true...and the shadows are one area where it really shows. I've got several more than 10 stops that have absolutely perfect shadows.
Hi Andy,
I do not need to go into the pitfalls / issues with that type of conversion, I will just give you a link to "Picturenaut":- http://hdrlabs.com/picturenaut/
It is a free programme that will convert to HDR.
For simple direct conversion:-
Start Picturenaut.
Load the jpg. (file > open)
Convert to 32 bit (Image > Mode > 32 bit per channel)
File > save as > HDR
At least you can have a play and see / test the results yourself.
Not as familiar with iray but I have used jpgs for image based lighting in Carrara and iClone and they work, I just import image map instead of HDR the shadows fall in the right places, probably trying to convert to a fake HDRI is more the issue than just using it as is for IBL.
I would watch this video by DimensionTheory on why JPGs are not good to use. Based on that information, I would seriously doubt you could create dynamic range from JPGs and need images that were created with dynamic range.
I found a way to use Skydomes with Iray. link below
http://www.daz3d.com/forums/discussion/54045/P30/#825295
This may help you because I use Skydomes for many of my renders too.
Hi Wendy, Cris,
sadly you are right.
I tried picturenaut. But the results are as bad as the various sources from deviantart. With DAZ-iRay nothing works.
We badly need the combination of sun-sky with dome maps. !!
Hi foks, me again.
Does really nobody know how to build new sky-maps for the iRay dome, which really work?
I found some in a link (HDRMAPS.com) of SickleYield's iray-tutorial. OK - they work, somehow. But the final resolution on the skydome is low and the sun intensity small (only weak shadow), although there is a deep blue sky with a very light sun.
And there are wonderful skydome maps from glaseye available on ShareCG, which only wait to be transformed into really working HDRIs.
So nobody competent out there ??
H E L P !!
Theres always Bryce
it can export 360 equilateral HDR renders
There is a very good amount of free HDRIs available. Have you tried these?
http://www.hdrlabs.com/sibl/archive.html
Hi Cris,
yes, I tried that link.
I used the DS360_Free_02 hdr. In the picture there is a very well defined and very shiny sun. But all i get in iRay is only a very blue environment and a little and really faint touch of shadow.
What's the matter? Why even don't the HDRIs of commercial vendors work?
First: The DS360_Free_02.hdr
Second: The result
Third: A similar situation produced with skydome, distant light, UE2 in 3Delight
Check with Picturenaut the actual dynamic range of that image. I have a similar DS360*.hdr and its dynamic range is less than 7 stops!!! It is not a HDRI image; it is a LDR (low dynamic range) image in equirectangular projection.
It is very very difficult to find real HDRI equirectangular panoramas around (I have found a couple of them, but they are small and therefore useless as backgrounds).
Hi Latego,
That's true. >:(And most you find are allready with a lot of landscape around. But if you have your own local environment (scene), you only need a free sky with sun / moon and some clouds.
Repeat the third without the Distant Light...and you will find that they are very similar. Adding another light in the 3DL render and comparing it to an Iray render of just the same midrange environment map is not a real or fair test. You need to match the conditions...
There are links to many HDR images in the long Iray threads...but
Most of these are mid to very high range, most will cast decent shadows. Quality and license, noted. Many of these sites also have pay versions that range from fairly cheap to rather expensive...but licensing is usually much more 'commercial' friendly for the paid versions and there are either higher range/higher res backplates with the paid ones.
http://www.aversis.be/hdri/ (monthly freebie, non-comm only) *
http://hdrmaps.com/freebies (several free ones, some are usable in commercial renders) *
http://vfxmill.com/vfxmill_freestuff.html
http://www.dylansisson.com/project/panoramas/ (non-comm) *
http://www.doschdesign.com/samples.php (possibly commercial use) *
http://www.hdr-sets.com/index.php/free-sets.html (non-comm)
http://www.hdri-hub.com/hdrishop/freesamples *
http://www.dutch360hdr.com/shop/ (varies...more than at the sIBL archive site) *
http://www.hdrmill.com/Freebies.htm (these are low to midrange) *
http://noemotionhdrs.net/
http://www.openfootage.net/?cat=212 (varies..quality and license...the pay for ones are very good..and pretty cheap. He also always has a render with the image that shows the shadows cast by the image) *
https://www.moofe.com/#/free (somewhat convoluted and restrictive Terms)
http://www.treddi.com/forum/files/category/2-textures-e-immagini-hdri/
http://www.hyperfocaldesign.com/free-hdri-sky/
http://gl.ict.usc.edu/Data/HighResProbes/ (of course, the 'granddaddy' of HDRI resources) *
http://www.sachform.de/index.php/free-downloads
http://www.turbosquid.com/FullPreview/Index.cfm?ID=925039&seo=0 (may be more on Turbosquid...)
http://www.food4rhino.com/browse?searchterm=brianjames+hdr (mostly seem to be non-comm)
http://www.zwischendrin.com/en/browse/hdri (no sort function I could find, the free ones are scattered throughout the pages)
http://adaptivesamples.com/category/hdr-panos/ *
Low to mid...some with very nice shadows, many spherical only
http://www.accustudio.com/exchange/hdri-p (
http://dativ.at/lightprobes/ (Non-comm) *
These are ones I know that are just low range/backdrop only...
http://blenderartists.org/forum/showthread.php?24038-Free-high-res-skymaps-(Massive-07-update!) (no restrictions, just sky maps)
http://www.evermotion.org/tutorials/show/7928/free-hdri-cd-collection-from-evermotion (variable quality, mostly just skies) *
http://shtlab.blogspot.com/2009/08/hdri-panoramic-skies-for-free.html (usable for lighting, created in Vue)
And these are nice for 'studio' shots...
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 *
http://jerrycrow.deviantart.com/art/Redspec-TGX-Official-HDR-Pack-01-453173341 *
http://zbyg.deviantart.com/art/Free-HDR-For-Studio-Render-157557355 (hi-res) *
* ones I've actually used and have had very good results with...the others I haven't used.
http://adaptivesamples.com/2013/11/17/how-to-create-your-own-hdr-environment-images/ (fairly good tutorial on creating HDR maps)
And I'm sure I'm missing some...
@mcj1016: fantastic list of links. I am going thru them and at least HDRI Hub freebies are top notch.
Hi latego,
thank you.
Some of the pics I checked had a value of >12. That of the example even's got 15.65 So this seems not to be enough?
But with picturenaut there isn't any way to influence / modify that value?
@mjc:
Why do you say, it wasn't fair?What do you need to build up a good sunny summer day?
- OK, some good friends, something to eat and drink, a comfortable beach, etc. - ;)
No honest:
There is the scattered light of the sky, the rebounced light of your environment (for 3Delight so far covered by UE2) and ...
... and the intense sunlight. And this is represented by a 70% distant Light for 3Delight.
So for 3Delight my setup is correct. For the suitable background I used a physical half-sphere (Skydome) with a corresponding sky-picture to complete the setup.
But now comes iRay.
iRay claimes to cover all that - you only have to select the suitable HDRI?
btw: I didn't use the same pic for iRay as I used for the 3Delight skydome. Here you got it wrong.
For iRay I tried various HDRIs of the diferent commercial vendors and sources named in the previous links.
Changing the render engine doesn't mean to change nature !!
OK, the next days I'm going to dig through the long list of links. Hope to find some pure sky HDRIs somehow similar motives like the 5 skydome serieses of glaseye (http://www.sharecg.com/pf/full_uploads.php?pf_user_name=glaseye).
Up to now I received the help of steve.athome who created one pretty good prototype out of one of these skydome pics.
Thank you again to him.
Hi,
me once again.
mjc: Thank you for the long list.
Some I allready tested.
I don't want to be negative.
But hdrmaps.com and dutch360 didn't work.
aversis.be works with vray, not iray.
Some others I'm going to test as soon as my long time render has finished.
The problem is, you are not comparing two HDR light set ups...you are comparing a 'sun' light to a low to mid range hdr and wondering why you aren't getting shadows.
You need to compare the same thing...either add a 'sun' to the Iray set up or use a high range hdr in both Iray and 3DL to compare. Until you do that, you are not getting valid results. And by NOT using the same image in both, that's even less accurate results.
To use an HDR map in Iray and get great results it must be 2 things...a true high dynamic range and if it is going to be visible as the backdrop, sufficiently sized (resolution) to not be blurry. Or add supplemental lighting, like you are in 3DL.
And one other piece of the puzzle...linear workflow. Iray falls to pieces in a non-linear workflow. That means properly using gamma correction...on everything. Textures need to set to the proper gamma and so on.
Please explain 'didn't work'...
And an hdri is an hdri, it is not renderer specific. I've used Averis images in Iray, 3Delight, Luxrender...and have had fantastic results in all of them.
Hi mjc,
I really have to contradict. I tried those HDRIs which were promissed to light the scene as shown in the promos. And related to hdrmaps.com and dutch360 you see the result in my comparing post.
But he sent me one of the offered HDRIs for testing, which i can do as soon as my long time render has finished.Meanwhile I received a mail from Wouter Wynen (aversis.be).
I know that it is possible to create HDRIs showing the expected result, because steven allready built one which was very close.
Andy
Hi again,
here is the result of the test map I received from aversis.be.
The rest are simple some adjustments within DAZ iray environment setup.
Both directions rendered with the same settings.
And are you satisfied?
Nice, crisp shadows...
Hi,
somehow ...
The HDRI itself works fine. But they don't have maps without other object in front of the horizon as I need for my sets.
And I think I detected further issues with the settings within DAZ itself.
You know: In the environment settings there are the two parameters "Environment Intensity" and "Environment Map". What is the idea behind that? It doesn't matter which one I modify; it ever changes the intensity of the light and the lightness of the skymap together in the same way.
If as an example I set the parameters 1:5 or 5:1 the outcome is ever the same. Similarly I could change the exposure time or F/Stop or ISO to have the same effect. :-S
So what if I want to adjust the intensity of the sun+envilight against the lightness of the sky picture? Because in the current example (it is only my subjective impression) the light in the scene is too dark compared to the lightness of the background (skymap image).
My next problem is to adjust the skydome to get the horizon in line with the virtual level of my scene. As I tried (for finite sphere) suddenly the skymap was cut off at the top (open sky). Or the light suddenly disappeared. There's still a lot I have to learn about the behaviour of these parameters.
Yes, the settings are somewhat confusing and not necessarily doing what one may think they should...and I'm not sure about half the Iray ones, without going back through the various threads to find them.
But a lot of your control is going to be in the exposure settings.
The dome controls are some of the hardest to master. And for a scene with a geometric ground, I find it easier to translate the entire scene up/down (parent everything to a null and move that) than try and use the various dome adjustments to match the horizons.