Using HDRI software to enhance Carrara renders
FractalDimensia
Posts: 0
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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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
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.
HI :)
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.
Could you tell us the section or page number of the manual?
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.
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.
Alternatively, could you output a RAW file and leave the rest to an external program?
Not as comfortable but possible a useable first step.
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! :)
Great job on that beautiful watch, 3dage!
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.
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....
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."
What about adjusting the gamma in the render room? Not elegant, but it is within Carrara and it is kind of adjusting the brightness.
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.
I tried that too. One limit is that you can't set the value under 1.0, which is the default for no gamma adjustment. So you can make it brighter, but not darker. The other problem is that it is not any different (as far as I can tell) from adjusting brightness/contrast in an image editor. That is not the same as adjusting exposure. Adjusting the gamma would allow you to bring dark section of the photo into the image, but it wouldn't help in areas that are "washed out" (over-exposed).
The "bright" image in the sample I created with my first post was done by gamma correcting to a value of 2.5, and then setting sky and indirect lighting (global illumination) values to 100% each. The "normal" image was done by turning off gamma correction, but leaving global illumination settings at 100%. The dark image was made by turning OFF global illumination settings. These (as my first post suggested) are the best results I have found so far to create 3 images I can use. It's not perfect, but I think it creates very nice images you can't get using "normal" camera/lighting settings.
I'm trying a few other approaches. I hope to be able to post a few more samples by this weekend to show the results.
I tried that too. One limit is that you can't set the value under 1.0, which is the default for no gamma adjustment. So you can make it brighter, not not darker. The other problem is that it is not any different (as far as I can tell) from adjusting brightness/contrast in an image editor. That is not the same as adjusting exposure. Adjusting the gamma would allow you to bring dark section of the photo into the image, but it wouldn't help in areas that are "washed out" (over-exposed).
The "bright" image in the sample I created with my first post was done by gamma correcting to a value of 2.5, and then setting sky and indirect lighting (global illumination) values to 100% each. The "normal" image was done by turning off gamma correction, but leaving global illumination settings at 100%. The dark image was made by turning OFF global illumination settings. These (as my first post suggested) are the best results I have found so far to create 3 images I can use. It's not perfect, but I think it creates very nice images you can't get using "normal" camera/lighting settings.
I'm trying a few other approaches. I hope to be able to post a few more samples by this weekend to show the results.
Yeah, I know it's not the same... I just said that, and I understand why.
I know you know this, but let's imagine a novice user is reading this discussion. Imagine a scene with a tree. To make an HDR you need exposures that capture the brightness of the surrounding terrain, which will create deep shadows under the tree obliterating any details. You will also need exposures set to show the details in the shadows, and a few more exposures in-between. The images are compiled into a single image that more closely mimics the dynamic range of what the human eye sees.
Now my idea: What if you adjusted the scene's ambient light which is set by default to twenty percent? Zero percent would be the deepest shadows. As an experiment, you could try a few renders with each one upping the ambient light from zero to twenty percent.
I am compiling a list of experiments to run trying different approaches. (Can't help it. I'm a scientist and have to follow the rules ;-) ) I'll add this one to the list.
ATM, I'm looking for a good DAZ-provided scene that provides the range of darks and lights needed to test this.
Also, since the basic questions I offered at the start of this thread are clear now, I will initiate a new thread with a new title more appropriate for the work ahead....
Thanks for all those who contributed their thoughts and ideas. I look forward to your contributions in helping find ways to improve rendering quality (until DAZ can find their way to enhancing output functionality).
That would be great.
Free Picturenaut tool supports 32bitsfloat TIFF and can do the conversion to HDR.
If you develop this plugin, I'll be your first customer.
Hello, if you are mainly interested in f-stop as a light inhibitor as opposed to a DOF tool then can I suggest a simulated neutral density filter placed in front of the camera?
make a small plane, place it in front of camera to block view, parent it to camera, make sure it neitrher casts no receives shadows, make all parameters in the texture room zero except for colour which you make black or grey , use the alpha channel to change the neutral density percent
I guess I don't understand what the OP is trying to accomplish...
You want to simulate changing the f-stop in the Carrara camera so you can generate three renders at different light levels, and from those images you want to create an HDR image that you will then use to light your Carrara render?
I guess I'm not seeing the point...
An HDR image used for that purpose generally is a 180 degree spherical image of an environment. Which is why, when you create one, you get a chrome sphere and take a photo of the reflection.
So I don't understand why you want to do this in Carrara....
Are you going to generate an environment scene, then take multiple exposures, generate an HDR, and use that in the same scene for lighting? I'm not sure I understand the goal here. If you have the scene with enough of an environment that you can make an HDR, why not just use that for your renders?
For me....
It appears that "OP" would like to take three Carrara renders, one under, one over and one currectly "exposed" and combine them in the software he mentioned to produce a HDRI simulated render. This render to be used as the final product - not to be used as HDRI file in Carrara.
I had a play with a variable ND plane last night and the Photomatix software. The results weren't too bad.
It's worth investigating if you hav trouble lighting your scenes to get a nice tonal range.
I have a feeling it would work better in B and W
Ahhh...okay, now that makes more sense. He wants that "HDR look". :)
Well, since he ruled out the two easiest and most effective methods IMO (vary the lighting or do it in post...) I think he's left with a bit of a challenge. Personally I'd try varying the intensities of the scene lights or doing it in post. Photoshop can do wonders in that department.
Although if it's more than just a fun exercise, it would be nice to see what "look" we're shooting for for a particular render. There are other ways to skin a cat. (no offense to any cat lovers...it's just an expression).
And by the way, aside from the obvious Photoshop tweaks you can do to get that HDR look, if you still want to play with the HDR maker software you can simulate adjusting exposure in an image using a Photoshop adjustment. So just take the regular render out of Carrara, run it thru PS and generate an over and under version, and voila, you can play with the HDR maker software.
EDIT: I just checked, and, suprisingly, the Adjustment is called "Exposure" :)
HI Joemamma :)
I mentioned this earlier in the thread,. but... the OP is still on the same route.
Photoshop is a Photo editor,. and in real life, sometimes the perfect image is over, or under exposed,.
The "Exposure" function in PS allows you to adjust that,. or,.. if you intentionallly want to create over or under exposed images you can obviously do that too.
Mark Bremmer did a tutorial video about this some time ago. so none of this is new,.
just not the way the OP wants to get there.
There is no such thing as a 180° spherical. :smirk:
well he is half right :coolgrin:
Not that I couldn't do the same in PS, but if there is no data in th original image because it was so badly lit initially, then you can't use PS to magick it up. So the various exposures could have a place in filling in detail.
First three renders all done in Carrara, btoom right blended in Photomatix - as you can tell by the watermark
There is also http://www.oloneo.com/
Can you use MASTER LIGHT to raise and lower all the lights at once by percentages?
EDIT MENU --> MASTER LIGHT... (the lights must be selected or within a common grouping)
This was originally my point. To be more precise:
(1) Adjusting the lighting for 3-4 various exposures is okay if you have 1-3 lighting sources. It becomes more problematic when there are a dozen or more. On this point, I particularly like the idea of putting a "lens filter" in front of the camera to adjust the lighting. This seems to be the perfect and easy way to adjust the exposure. I have not had a chance to try this, but given my limited knowledge of Carrara, would seem to work. Thx, Head! The "Master Light" settings I was not familiar with. Thanks for that idea also Holly!
(2) As you mention, PS can't work wonders where there is no data. And since Carrara saves files in 8-bit colors, there are limits to the adjustments you can make. No software (currently developed) can overcome some limitations.
(3) The end result of what I am looking for are images of greater depth and range in color. Until we can save 16-bit color images in Carrara, I have been examining alternatives that will get me closer to that.
Hopefully soon, DAZ will obviate the need for such efforts in the near future! :D