Can Carrara make HDRIs?
RobotHeadArt
Posts: 916
I picked up Carrara in the sale and am trying to learn more about what it can do. Can it render spherical HDRIs that can be used in DAZ Studio Iray as domes?
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Good question, straight out of the box, not that I am aware of.
Maybe this will answer part of your question.
Here is an image from Carrara which was rendered using HDR
For the HDR in the image I used an 'HDR' made in Carrara.
I did it by rendering several images of a forest with the Carrara spherical camera, for each image I used a different gamma setting then combining the lot in Oloneo (HDR program) and outputting an HDR file, then using that to render this scene (thios scene comes with Carrara with it's own HDR).
Of course there is probably a big difference to what I am doing and a real HDRI ;)
But it seems to work okay.
In this Carrara scene the HDRI was cranked up to 1000 percent which is why the glass ball is washed out???
Sorry dont know anything about Daz Studio except that Daz gives it away for free ;)
Yes it can. Just set the camera to spherical, and the image size to something suitable (say, 8000x4000), and off you go. You'll need to create a bunch of renders with different exposures and stitch them together with appropriate HDRI software. There's a discussion of HDRIs in this thread, although you wouldn't guess it from the title! http://www.daz3d.com/forums/discussion/66694/do-you-iray/p1
Attached is a very quick and dirty (and small!) spherical render of the scene I had loaded as I typed this reply.
Great! Thank you for the information!
PhilW's Advanced Carrara Techniques has good instructions on how to render the needed images and demonstrates the HDRI creation process using PhotoShop
Carrara can use SkyLight for spherical image maps as well as spherical HDRI
Carrara's Spherical Camera makes great spherical maps! :)
It's a track I've been following for some time now. The main problem is that Carrara won't accept Gamma settings below 1, which would be necessary to provide the underexposed view HDR creation programs are expecting, but somehow, I've got correct results. Personally, I use Luminance HDR
to combine the renders and create the HDR file.
For now, I use the Luxrender plugin to create HDRI. I would love to use Luxcore but, unfortunately, Luxcore programmers (Luxcore itself, not the plugin) somehow missed the spherical camera in their implementation.
Cool. That's pretty much the same procedure I use (as HeadWax). Rendering without Gamma Correction should give the below Gamma result you need if you don't include too much indirect lighting or ambient setting. For low exposures, just try and keep away from Global Illumination (SkyLight setting in render room) with nice, dark shadows where you need them to be. Then go ahead and crank that stuff up for the high-exposure frame(s) you need - so long as the light source(s) needed remain prominent throughout - I think. It certainly takes a lot of practice.
Must be a few approaches to get the initial renders for the HDR
Just tried two distance lights on a scene, one the main light, one a fill light.
Then did various renders where both lights were on,
then one off, then the other
then changed one to a negative light
kept the other as a positive light
(and vice versa)
combined all images as HDR
worked okay!
Yup. I imagine how intense the light source(s) will be at low exposure through mid to high. Assemble, tweak, save.
Both of these were rendered in Iray using HDRI I've made using Woodlands Panoramic Maker
Both had the HDR light intensity cranked to over 400 to make that blown-out look
Hmmm, I was always under impression that exposure and gamma are two different things ...
As far as I understand it, exposure should be property of camera itself and gamma is post-processing (non-linear) of the image after the fact.
I suppose, since Carrara's camera is not phisycally correct (it is a single point in space, I believe), it does not matter anyways ...
My 2 cents on the subject, lol
You have that correct, Fifth.
In an HDR shot, your using lense speed settings to determine the exposure. Sickle Yield had a cool video about HDR and Iray, which is interesting as long as you're into HDR imagery, no matter what render tool is used. Aperture, ISO, and Shutter Speed.
Lower speeds let in less light, which is why we use super long exposures to capture images of deep space objects with sophisticated motor driven guiders controlled by a special Guide-Scope, which holds the lens on the target over extended times.
For the minimum we need three exposures. Low, medium, and high, but more can be used for even higher precision. The .hdr format is special in that it allows us to go (WAY) beyond 255 in the RGB spectrum. 255 is white, so for most image formats, that's maximum. But .hdr is special and can use those higher numbers to isolate areas that are not only bright, but are also emitting light (by going beyond normal limits).
You're right, of course, The idea came when I was looking at the model used by Picturenaut (a free HDRI program) to combine LDR shots with different F-stops. The curve it used between f-stops looked pretty much like a Gamma curve. So, I went for:
What is lacking is a gamma 0.5 to make a F-2. I can fake it with Gimp, but it's just that, faking...
The main issue with Carrara is that the lighting information is lost. It's even more true if you're using invisible light source like bulb, spot, sun, distant.
I have made a few feeble attempts using the spherical camera in Octane and changing the F-stop of the camera
then combining in Picturenaut, but not really thrilled with my results over just a plain spherical rendered image.
That's the thing, JaguarElla, and it takes a lot less time to make! :)
Just to add that if you have Octane Render for Carrara, that can render and save HDRI spherical images directly with no processing needed (other than to convert from EXR to HDR file format).
Well now...
This answers the actual original query, doesn't it! :) Thanks for this, Phil!
As an aside off-topic: I was just thinking of you. My band is back in practice mode with a different configuration to enable our core members to gig a bit more often, which has brought back some great memories of the old days. Learning new songs at a rate that keep the heart beating constantly is quite refreshing! Too bad you didn't live just a little closer, would be fun to drop you into the mix! My singer is also a sound engineer and his studio is now fully set up for my movies' voice tracks needs. Should be a lot of fun!
I thought EXR just a diff image format not nessessarily HDRI
That's right. So Picturnaut should be able to open it and save it back out as .hdr, I think(?)
Never tried that.
Here's a tonemapping tutorial from the Luxrender wiki
HDR with Luminence
Note: The above tonemapping tutorial also demonstrates how to use Luminence to work with your EXR files
EXR is another type of high dynamic range file format, just an alternative to HDR. An HDRI file doesn't necessarily have the extra lighting info in it either - you could create a blank document in Photoshop, fill it with one color, convert it to 32 bits/channel and then save it as .HDR or .EXR - the file format itself doesn't necessarily mean it is a high dynamic range image for either one, just that it could be. I think the main difference between the two formats is that .EXR can also store layer/channel information (like a depth pass for example) so it's not only potentially hdr but can be used for compositing.
I don't have Picturenaut, but I know Photoshop can do this, so I image it can too.
It's not that HDR automatically creates lighting maps, per se... it's the fact that it allows higher ranges of brightness than other image file types, which will allow HDR artists to create the place(s) where the light comes from, how much, etc.,
Right - I was just saying that EXR is just another format that allows you to do the same thing. Neither format by itself means the information is automatically in there, but they can both contain it.
Ah yes.
Also, if you have Luxus for Carrara you can use LuxRender to create true HDRI straight from your Carrara scenes. Tweak out lighting during render, tweak out tone-mapping while rendering, many other very useful features.
It exports to the Open Source .exr format which, as explained above, is a type of HDR format
Thanks all. I made a "fake" HDRI: render Carrara scene, save as TIFF, open in Photoshop, convert to 32-bits, save as HDR, set it as environment map in DS and IRAY render.
So it's not a true HDRI image but it does give some nice results regardless. As I learn more about Carrara and all these other nifty tools I'll probably have to expand into the LUXUS/Octane playroom, but for now, just out of the box, this is very cool. Just for backgrounds alone it was worth it. And here I'd spent WAY more on backgrounds from D3D and I could have been doing this....<face-palm>
attachments: 768x768 iray test render. volleyball re-shaded with iray metal shader, environment map created as above. That's not bad at all for being fake-HDR. for now :)
3rd attachment: DS Reality -> Luxrender. volleyball set to Mirror, Lights set to IBL "my fake HDR". 3 minutes running (because this is just a comparison). Not bad at all.
4th attachment: DS Reality -> Luxrender...(same config only camera is looking towards the sun). I guess whatever additional lighting information is in a true HDR shows it is missing when looking at the light source. No bloom or wash-out, just the sun object in the sky.
So using it in DS (which does show some light blooming) gives a nice, simple effect. I wonder if Luxus would be able to generate the full HDR (32bit) image. I know it launches Luxrender, but would the Carrara sun settings carry enough information through Luxus->Luxrender for an actual HDR?
Just a cool little tip if you want to try it, is to set one of the lights in your scene as a Sunlight. It behaves a lot like a distance light, except that you can't set the color. The light is aligned with the sun disk in the Realistic Sky Editor (RSE), and will take its color from the position in the sky. So a sunset would make it more orange.
The other cool thing about it, is that if you select the Sunlight and then go to the effects tab and click the lens flare editor, you can select from a pulldown menu of lens flare presets. There are two different sun lens flares. They align perfectly with the sun disk in the RSE.