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Using HDRI software to enhance Carrara renders
Posted: 05 February 2013 10:50 PM   [ Ignore ]
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I recently started using Photomatix on my renders and got (what I think are) some interesting results. I used a basic DAZ provided scene to test the idea. I generated one image at normal exposure, and then simulated 2 more renders - one over and the other under-exposed. I then used Photomatix to create an “HDRI” image. (See images below. The first 3 are Carrara rendered; the last (reduced to 8-bit imaging) was produced through Photomatix.

I am relatively new to Carrara, but I was wondering if anyone else has been experimenting with using HDRI software to enhance their Carrara renders.

Along with that, I have several questions related to this topic and maybe someone can offer their experiences on it. Please provide some illustrations to help, if it is not too much trouble.

1. The Carrara 7 User’s Guide refers to setting the f/stop for cameras, but I cannot find such a setting on my Carrara V8. Am I just not finding it or is it gone? If it is no longer there, how do I go about under and over-exposing renders?

2. Are there settings for cameras (that I am not aware of) that will produce render results similar to what an app like Photomatix will produce?

3. Does anyone know if there is anything in the works for a future Carrara version to render HDRI quality images?

Thanks in advance for your feedback!

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Posted: 06 February 2013 12:00 AM   [ Ignore ]   [ # 1 ]
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Carrara can used HDRI directly. scene effects/background/HDRI. Well you have to have some HDRI to use to lol http://hdrlabs.com/sibl/archive.html

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Posted: 06 February 2013 06:47 AM   [ Ignore ]   [ # 2 ]
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What ManStan is referring to is using images for lighting (HDRI environment maps) while you are referring to creating a high dynamic range (HDR) image from Carrara—not exactly same thing. To my knowledge you cannot create an HDR image directly in Carrara, but would have to do as you have done.

IIRC, Carrara is actually HDR internally but it doesn’t support saving as anything other than normal images. Which seems rather a shame as the renderer wouldn’t have to approximate using multiple exposures, it could simply record the values. Fenric, or someone else more knowledgable about Carrara’s inner workings, could better answer that aspect.

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Posted: 06 February 2013 11:09 AM   [ Ignore ]   [ # 3 ]
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HI smile

Carrara doesn’t currently export in any 32 bit formats,. so, no, you can’t make HDRI’s in Carrara,. But,.. you can make 96bit HDRI’s using Bryce.

Carrara can use HDRI’s or can use 8 and 16 bit images colour values and colour gradients in the SCENE / BACKGROUND slot.
and if you enable SKY LIGHT in the rendering settings, then carrara will use that Colour / Image / Gradient / HDRI,. to illuminate the scene.

If you want to use Carrara to make your own HDRI’s, then the best method is to create a Spherical camera (to give you a 360 degree spherical environment image) ,. and then render out a large image of your scene,.. EG 8000 x 4000, ...which you can then take into photoshop,. ...create a couple of different copies of that image… then you can easily change the exposure in Photoshop, then use photoshop to blend and create an HDRI.

The easy option is to buy a set of high quality photographic HDRI’s like Dimension Theory’s sets, or Magaremoto’s sets from the store here,. or download a couple of free HDRi’s from the web, there’s many different places with free HDRI’s.

Carrara also ships with a couple of HDR Images, which you can find in the “Global illumination!” folder of the Preset Scenes, from the Carrara Native Content.

Hope it helps ...

Also,. here’s the last thing I rendered using HDRI ...mainly for the reflections.

 

 

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Posted: 06 February 2013 11:21 AM   [ Ignore ]   [ # 4 ]
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1. The Carrara 7 User’s Guide refers to setting the f/stop for cameras, but I cannot find such a setting on my Carrara V8. Am I just not finding it or is it gone? If it is no longer there, how do I go about under and over-exposing renders?


Could you tell us the section or page number of the manual?

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Posted: 06 February 2013 11:50 AM   [ Ignore ]   [ # 5 ]
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I can’t find where f-stop was mentioned but wasn’t Lens Size renamed to Blur Intensity in Camera Properties>Effects>Depth of Field>Edit? The functions are the same I think as an f-stop would perform many of the same functions in a real camera except for the amount of light coming in for Carrara. An f-stop would change your depth of field/blurriness. A “0” Blur Intensity setting would give you a sharp image from front to back.

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Posted: 06 February 2013 01:12 PM   [ Ignore ]   [ # 6 ]
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Kevin Sanderson - 06 February 2013 11:50 AM

I can’t find where f-stop was mentioned but wasn’t Lens Size renamed to Blur Intensity in Camera Properties>Effects>Depth of Field>Edit? The functions are the same I think as an f-stop would perform many of the same functions in a real camera except for the amount of light coming in for Carrara. An f-stop would change your depth of field/blurriness. A “0” Blur Intensity setting would give you a sharp image from front to back.


I don’t know what it was before Carrara, but in RayDream Studio 5 the interface was nearly identical, except I think you had a near cross-hair, a middle cross-hair and a far cross hair. I even think it was called Depth of Field, or DOF, though I wouldn’t swear to it.


The nearest thing I can think of related to exposure in Carrara would be Gamma Correction in the Render room, though I thought that had more to do with monitors.

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Posted: 06 February 2013 01:34 PM   [ Ignore ]   [ # 7 ]
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Yes, internally Carrara stores image data as 128-bit RGBA (4 channels, 32-bits each)

The bad news is that the SDK does not have a base class, sample, or documentation on how to create an image format plugin.

The good news is that the required interfaces and header files ARE documented, and I’ve already figured out how to do it.  :D

The “meh” news is that HDR file formats all suck to implement.  OpenEXR might be do-able, ILM’s library is free and doesn’t look too bad… but I’m already pulling my hair out from the list of “now go download this… now go download that… dependency crap that so many things have.  Radiance (.hdr) doesn’t really have a nice library that I can find, so I’m downloading Radiance itself to see if I can’t yank the code out of it.

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Posted: 06 February 2013 02:26 PM   [ Ignore ]   [ # 8 ]
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Alternatively, could you output a RAW file and leave the rest to an external program?

Not as comfortable but possible a useable first step.

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Posted: 06 February 2013 03:35 PM   [ Ignore ]   [ # 9 ]
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3DAGE - 06 February 2013 11:09 AM

HI smile

~snippy snip snip~
Also,. here’s the last thing I rendered using HDRI ...mainly for the reflections.

By the way,
For those who don’t already know, 3dage made that watch in the Carrara model room.
I’m hoping that he’ll model the innards, too. when he does, it’ll be time for me to buy a 3d printer and make the watch for real! smile
Great job on that beautiful watch, 3dage!

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Posted: 06 February 2013 03:49 PM   [ Ignore ]   [ # 10 ]
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Actually: I’ve found that 32-bit float is supported in TIFF files, and libtiff has a nice example -  I think that might be best.

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Posted: 06 February 2013 05:42 PM   [ Ignore ]   [ # 11 ]
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evilproducer - 06 February 2013 11:21 AM

1. The Carrara 7 User’s Guide refers to setting the f/stop for cameras, but I cannot find such a setting on my Carrara V8. Am I just not finding it or is it gone? If it is no longer there, how do I go about under and over-exposing renders?


Could you tell us the section or page number of the manual?

Okay, I must have been hallucinating, because NOW I cannot find what document I read it in. I remember it being referenced just under the “Depth of Field” description under camera effects.

I guess the most important point of my original post is the following:

*** “How do I simulate the effects of changing the f/stop value in a REAL camera?” ***

And BTW, f/stop as a number refers to the ratio of the focal length to the aperture diameter, and represents the amount of light being “let into” the camera when a photo is taken. In other words, I want to be able to adjust the amount of light being “let in” to the Carrara camera. I would prefer to not do awkward things like adjusting the lighting or post-editing the photo in Photoshop or other tool, but instead would like to only alter the camera. Of course, after some further searching, it seems that is not possible. Since you can set the distance to near plane (which I interpret as “focal length,” it would also be nice to adjust the aperture to get f/stop settings (or to adjust the f/stop value, which in turn would effect both aperture and focal length).

I appreciate the discussion and hints about USING HDRI files as an input to Carrara, but I am aware of these options. I am more interested in creating HDRI (like) images [like the one I offered in my first post] in the simplest means possible.

Thanks to all for your comments and feedback….

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Posted: 06 February 2013 05:54 PM   [ Ignore ]   [ # 12 ]
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It seems (as I suspected) I’m not the first to request this. I did find the following posts/reference on the “historic” forum site related to things mentioned here (initiated by DAZ_bfurner on the DAZ publishing team Apr 2011) on new features. I guess DAZ hasn’t gotten around to these yet…

http://forumarchive.daz3d.com/viewtopic.php?t=162543

Dimension Theory stated:

“Can’t believe this wasn’t first and foremost…

Feature:
32-Bit Rendering Format

In Depth:
Should be a give in. I really can’t believe we’re still restricted to 8-bit renders. Bryce has a much higher bit depth and exports to HDR. Fredric has brought up the fact that it’s rendered as 32-bit internally. Give us access to an export format that allows decent amounts of editing.”

Also in that thread:

ExtruD stated:

“Camera:
(Feature) Camera/lens setup presets
(Feature) F-stops, shutter-speed settings which replicate real world camera effects, like depth-of-field, and motion blur, replacing the current and inaccurate depth-of-field effect settings.”

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Posted: 06 February 2013 05:55 PM   [ Ignore ]   [ # 13 ]
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What about adjusting the gamma in the render room? Not elegant, but it is within Carrara and it is kind of adjusting the brightness.

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Posted: 06 February 2013 08:52 PM   [ Ignore ]   [ # 14 ]
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Adjusting the gamma is not the same as adjusting exposure. Two very different things—brightness is effectively a global add/subtract whereas gamma is more of a curve. And, I think for most purposes, gamma is a more useful control by retaining the brightest/darkest values. As such it isn’t really suitable for simulating exposure.

Being able to produce HDR images directly from Carrara just makes sense. At least we have Fenric to pick that ball up. (Although I have no objection should Daz decide to implement the support themselves.)

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Posted: 06 February 2013 09:00 PM   [ Ignore ]   [ # 15 ]
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thoromyr - 06 February 2013 08:52 PM

Adjusting the gamma is not the same as adjusting exposure. Two very different things—brightness is effectively a global add/subtract whereas gamma is more of a curve. And, I think for most purposes, gamma is a more useful control by retaining the brightest/darkest values. As such it isn’t really suitable for simulating exposure.

Being able to produce HDR images directly from Carrara just makes sense. At least we have Fenric to pick that ball up. (Although I have no objection should Daz decide to implement the support themselves.)


I know it’s not the same thing. I said it may be the closest, inelegant solution at the moment. I also agree that having the ability to render an HDR would be a great feature, as well as more modern camera controls, however, as it stands we don’t, and since the OP was looking for a solution, that’s what I suggested.

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