VraySemiPhysicalCam

[DuskZero]

There's a few posts here about the Physical Cam. Its a great addition to Vray and I use it all the time, and I understand that it has been made as true-to-life as possible, but the last two animation jobs we've done it has caused a lot of headaches.

I'd love to have a VraySemiPhysicalCam that has the exposure and vignetting available, but allows you to stop the target distance affecting the brightness of the image or the field of view. Having all the extra parameters to change just to keep a stable brightness and field of view when changing focus can be annoying in animation, and results in spending extra time in both 3D and post tweaking colours and exposure.

The ideal way for doing this would be to have a checkbox which stops the target distance doing anything but setting a focal range. Alternatively, a separate camera type which doesn't have all the physical settings, but does have exposure and vignetting.

The main advantage of the physical system is that you can work in an HDR environment (eg with VraySun/Sky) easily and quickly. I'd like to be able to keep this but not be constrained by all the physical rules.

Sam

[beestee]

I would like to add to this wish...orthographic projection.

I can get extremely close to orthographic with a .001mm film gate and the camera placed some 15'000 feet from my building(I feel that I am breaking what would be physically possible in a real-world situation anyways with this approach), but I still get a small amount of perspective distortion.

And (slightly OT ) I would like a toggle for visible representation of the clipping distances.

[^Lele^]

why not use a standard max cam, then, colormapping for exposure, and a pre-rendered vignette effect to comp over linear RGB imagery in post?

[DuskZero]

Hi Lele, thanks for the suggestion.

Indeed, dialing the multiplier on Reinhard down to 0.02 gives a similar result to the physical cam through a max standard camera. Makes it a touch fiddly to tweak small amounts, but it the results are good. Though it made me notice that it would be good to have the white balance, still, under sun and sky.

Cheers,

Sam

[^Lele^]

indeed, but if you save linearly, you could do WB in post.

[DuskZero]

Indeed, but its not ideal to have to go to post when checking lighting every time.

For what its worth, I'd still like to have a version/option of the physical Cam that doesn't have the connection between target distance and exposure/FOV.

Sam

[^Lele^]

well, i'd say it would be worth it to try and go the mR way for exposure, ALONG with having the physcam.
That would allow for realtime exposure adjustment, as well as white balance.
I was thinking of scripting a plugin exposimeter that worked so, but haven't gotten around doing so yet.

[MoonDoggie]

Indeed, but its not ideal to have to go to post when checking lighting every time.

For what its worth, I'd still like to have a version/option of the physical Cam that doesn't have the connection between target distance and exposure/FOV.

Sam

I'd second this. It's a huge pain in animation to worry about my shutter speeds and target when rendering with a phys cam. Which is why I haven't gotten to use DOF or Motion Blur with it, because it's just a pain when animating.

[^Lele^]

Ok, a VERY EARLY attempt at a (semi)realtime exposer is here.
There are a few things not quite working as they should, due to my own ineptitude, but it does work quite nicely once setup.
download the script from here , and follow these steps carefully.

* check the bitmap save option in the render dialog, choose to save a bitmap as EXR, HDR, or any other 32bpc format, and render. This is needed because i seem unable to initialise a floating point framebuffer from within the render effect script. Not doing so will result in the image color being clamped to 1.0, and in the case of a sun+sky, it will make the effect expose to nice shades of gray.

* set the output size to something small, say 160x120 or thereabout. This is because the effect is applied as a post one, and having bigger images will be quite slow. on an x2-4200 at 160x120 the effect works in realtime.

* finally run the script, go to the render effects panel (rendering->effects) and choose to add "Lele's Vray Exposer".

* set the effect to interactive, it will render the bitmap, and allow you to expose at will, while updating it.

To have it automatically added to your set of render effects in future max sessions, put the script into your maxroot/stdplugs folder.
It's a toy, for now, with some sharp corners at that: DO NOT USE IN PRODUCTION.

[percydaman]

is it possible to implement a sort of delay, like when your looking through your digicam viewfinder and move it around, it takes a split second to reexpose? Might be a cool feature.

[^Lele^]

I actually managed to do a step further from the original.
I guess it can now be used as a semi-interactive tool to decide what's the ISO on a camera are going to be @ rendertime.
Basically it can be used as a viewfinder on dSLRs.
Remember to turn it off, or delete it entirely, if you choose to modify the Physcam ISOs, to avoid double exposure (camera and post effect).
Everything written for the original version holds (choosing a floating point format from the render dialog, even without rendering, and so on).
Based on some tests i did, it's a lot more convenient -as in a lot quicker- to render out a PPT preview for this, rather than the standard, multi-pass approach.
Get it here