NCCA student Zeno Pelgrims takes us through an in-depth tutorial of how he created 3D Still Life in Maya and ZBrush
I recently finished my still life image, so decided to do a quick breakdown of what's going on in the scene! I will go over the whole pipeline, from shooting the backplate and capturing the lighting information all the way through to compositing.
Shooting the backplate and capturing the lighting information
After I knew what I was going to do, it was time to shoot backplate and capture all the lighting information.
For this I used:
- Canon 5D Mark II
- 50mm 1.4f
- 8mm 3.5f fisheye
- Tripod with a panoramic head (One that clicks every # of degrees. Very useful when creating HDRs)
- Chrome & grey sphere (to check my lighting)
- Macbeth chart (to calibrate my colors)
The first thing I did was to try and make a composition that was less or more pleasing to the eye in real life, maybe trying to get some happy accidents in that occur MUCH more often in real life than in 3D. I also used it as my main big reference to shade objects. All in all, this is a very useful thing to do even if you're not using any of it in your 3D scene.
Shooting the backplate was very straightforward. I shot: a clean one, one with lighting checkers and one with a color checker. Something to note is that your camera has to be on manual mode. You do not want to have different settings for each of these shots. They all need to match!
Also ALWAYS shoot in RAW for these kinds of things. You don't want to have a compressed .jpg before you've even started.
The following pictures are shot in a really bright sunny environment, even though they don't really look like it. They're just as raw as it comes out of my camera sensor, and need some grading work to make them pretty again.
Color checker (Macbeth chart)
These days I try to use Nuke
as much as possible, steering away from Photoshop
as much as I can. This gave me a problem ? by default Nuke doesn't read Canon's .cr2 raw files. I turned to DCRAW, an open source piece of software that you can access from the command line once installed. It reads ALL raw formats and converts it the input into a 16bit tiff.
Later on I learned that also NUKE can use DCRAWs code. Just put the DCRAW files into your nuke directory in your home folder, and enjoy reading in .cr2 files in Nuke! You even get an argument line in your read node where you can enter your options for DCRAW. Super sweet!
Shooting the HDR
Once the backplate had been shot, it was time to capture the lighting information in the room. This is most commonly done by using a fisheye lens (because of the extreme wide angle), and shooting at least three exposures for every angle, for the full 360 degrees. You can shoot every 120°, 90°, and 60° ? it's entirely up to you! Just keep in mind that you do not want your lighting to change or your objects to move during the shoot. I personally went for 6 angles because I was the only one in the room and there were no clouds. Probably as easy as shooting an HDR gets!
Once again, I made sure my camera was set as manual as possible. I even chose a white balance setting just to be consistent across all my images, even though it makes absolutely no difference for raw images.
Using the panoramic head of my tripod, I shot three exposures (called exposure bracketing) for every angle. I did this using a little two second timer. Three Exposures really is the bare minimum, you should shoot more if you can. The camera I used with the default OS just can't do more than three.
I placed my Macbeth chart within a sunny area of my environment, so I can color calibrate the HDR to my photographed backplate (explained later on).
After the shoot I ended up with 18 .cr2 images. I stitched them together with an incredibly neat piece of software called PTGui
PTGui outputted me the following 32bit EXR. Great ? but not there yet. The highest floating point value within the image was only 4 (keep in mind that 8 bit images can only store values between 0 and 1). I used a Nuke gizmo called mmColorTarget to match the values of the Macbeth chart in the HDR to the values of the Macbeth chart in my backplate (read more about this on the renderblog
), and this boosted my max floating point value up to about 240.
Raw out of PTGUI: Max floating point value: +-4
After tone mapping the image (rather fancy word for grading it): Max floating point value: +- 240
A high value like this is great; it gives you nice crisp shadows. No need to fake this using CG lights! After the calibration, I color graded it a bit more for artistic purposes.
So that's my HDR image sorted. Great! Just a couple more things and we can move into 3D space.
First thing I had to do is color grade my backplate a bit for artistic purposes. After that was done, I had to undistort the image. Real lenses always have their own lens distortion.
Undistorting this is easy because of the already available algorithms in Nuke. I just printed off this grid and snapped a picture of it at a 90° angle, then read it in Nuke and used a lensDistortion node to analyze this grid, copy pasted the node and plugged it into my main node network. Easy! Ready to be used in 3D.
Before & after of the grid