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Using HDRI software to enhance Carrara renders
Posted: 06 February 2013 09:00 PM   [ Ignore ]   [ # 16 ]
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evilproducer - 06 February 2013 05:55 PM

What about adjusting the gamma in the render room? Not elegant, but it is within Carrara and it is kind of adjusting the brightness.

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.

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Posted: 06 February 2013 09:28 PM   [ Ignore ]   [ # 17 ]
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JimDHart - 06 February 2013 09:00 PM
evilproducer - 06 February 2013 05:55 PM

What about adjusting the gamma in the render room? Not elegant, but it is within Carrara and it is kind of adjusting the brightness.

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.

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Posted: 07 February 2013 05:11 AM   [ Ignore ]   [ # 18 ]
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evilproducer - 06 February 2013 09:28 PM

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 wink ) 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).

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Posted: 08 February 2013 01:54 AM   [ Ignore ]   [ # 19 ]
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Fenric - 06 February 2013 03:49 PM

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.

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.

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Posted: 26 February 2013 09:23 PM   [ Ignore ]   [ # 20 ]
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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

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Posted: 28 February 2013 01:41 AM   [ Ignore ]   [ # 21 ]
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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?

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Posted: 28 February 2013 02:33 AM   [ Ignore ]   [ # 22 ]
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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.

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

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Posted: 28 February 2013 03:22 AM   [ Ignore ]   [ # 23 ]
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head wax - 28 February 2013 02:33 AM

This render to be used as the final product - not to be used as HDRI file in Carrara.

Ahhh…okay, now that makes more sense. He wants that “HDR look”.  smile

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).

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Posted: 28 February 2013 03:42 AM   [ Ignore ]   [ # 24 ]
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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”  smile

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Posted: 28 February 2013 08:27 AM   [ Ignore ]   [ # 25 ]
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HI Joemamma smile

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.

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Posted: 28 February 2013 11:24 AM   [ Ignore ]   [ # 26 ]
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JoeMamma2000 - 28 February 2013 01:41 AM

An HDR image used for that purpose generally is a 180 degree spherical image of an environment….

There is no such thing as a 180° spherical. smirk

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Posted: 28 February 2013 11:30 AM   [ Ignore ]   [ # 27 ]
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well he is half right   cool grin

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Posted: 28 February 2013 02:35 PM   [ Ignore ]   [ # 28 ]
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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/

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Posted: 28 February 2013 04:00 PM   [ Ignore ]   [ # 29 ]
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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)

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Posted: 28 February 2013 04:02 PM   [ Ignore ]   [ # 30 ]
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head wax - 28 February 2013 02:35 PM

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/

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

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