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HDRi lighting workflow

Following on from a tip I first saw on Bertrand Benoit’s blog , I have now adopted a new method of loading my HDRi skies.

Essentially you can increase the apparent strength of the sun (and therefore get stronger shadows) by changing the gamma of the loaded HDRi map.

If you use the vrayHDRi map (which I now prefer as you can adjust the rotation in degress) then it’s a simple matter of changing the gamma from 1 to something lower. Through trial and error I have found 0.75 to be a good compromise. Any lower and there is a risk the sky can become too saturated and contrasty. Something between 0.75 and 1 should suit most skies.

vrayHDRi

If you use the 3dsmax bitmap loader, you change the gamma of the loaded file as follows (note that you need to enable the gamma/LUT correction in 3dsmax preferences):

bitmap

Here is a quick comparison of gamma 1 and gamma 0.75. The main advantage for me is a punchier image, and that you dont need to use a 3dsmax sun in addition to the HDRi sky. All of the products I sell on 3docean have a very high dynamic range compared to most products on the market, so bear in mind you might not get such strong shadows with other HDRi skies.

gamma 1:

gamma1

gamma 0.75:

gamma0.75

HDRi lighting & glossy reflections

If you are using vray and sometimes find that when using a vray dome light as a light source you get pixelated reflections of the sky, try this:

Select your light and type the following in the MaxScript listener:

$.dome_visibleOriginal=2

That comes from Vlado on the chaosgroup forum, he goes on to explain:

It just controls when the dome texture will be evaluated fully and when the values will be taken from the pre-sampled version specified by the “resolution” parameter. The presampled version is calculated faster, but is jagged. A value of 0 means that the pre-sampled version is used always; a value of 1 means that the presampled version is used for GI and glossy rays, and a value of 2 means that the presampled version is used only for GI rays. 2 should probably be the default, now that we have it.

I have never really noticed it, because the places it might show up (architectural glazing for example) I usually dont use glossy reflections. When I say glossy reflections, I mean any vray material with a glossy reflection value of less than 1.

Here is an example of the problem:

glossy

and fixed with the secret maxscript code:

glossy_with_fix

Hope that’s useful to someone!

Happy Holidays!

julkort

Wishing all readers of this blog a Merry Christmas and a Happy New Year! God Jul och Gott Nytt År.

Thanks for your continued support & comments and I promise I’ll try to update things here a bit more often in 2012!

The above image is a bit of a mash up of different things (alpine cabin plywood, ‘twins’ landscape) with a plywood Christmas tree that I found on build blog.

3D World CG Awards 2011

3D World CG Awards 2011

I’m proud and happy to have been nominated for the inaugural 3D World magazine CG awards in the arch viz category.

Lots of talented artists and companies there, remember to get your vote in before the 11th of August!

cgawards.3dworldmag.com

Perspective correction techniques

I’ve been neglecting my blog lately due to having too much work to do, so to try and get back into the swing of things I though I might as well put this up here (even although its not a tutorial).

I like to do as much as possible in Lightroom when it comes to processing photos, its so handy to keep everything raw and then even when I do need to make a jpg for uploading to the internet I tend to bin them afterwards. One thing that annoys me though is how LR does perspective correction. In my opinion PTlens (a cheap plugin for photoshop) does it well, in that it looks believable, whereas LR’s output always looks a bit squashed.

The two programs clearly use different algorithms, but which is more ‘correct’?

Lightroom:

LR

PTLens:

ptlens

and a comparison between the two showing how much taller buildings appear in PTLens:

comparison

I don’t have aperture but would be interested in knowing how it handles it. Also, if there is a way of stretching an image in LR please let me know! Otherwise, I must say I am very pleased with the lens correction presets in LR (for barrel distortion correction).

My workflow just now is to camera match with the uncorrected version in 3dsmax and then do PC control afterwards in photoshop. How do you camera match a TS Lens in 3dsmax, is it even possible? (with a degree of accuracy)