In my next Patreon video I will explain how to capture HDRIs for lighting and lookdev in visual effects. Then we will process all the data in Nuke and Ptgui to create the final textures. Finally everything will be tested using IBL in Houdini and Karma.
This video will be available on my Patreon very soon. Please consider becoming a subscriber to have full access to my library of VFX training.
https://www.patreon.com/elephantvfx
Thanks!
on-set
Dealing with lidars /
Hello patrons,
We haven't talked that much about lidar scanning, and it is time to say a few words about it. Lidar scans are a fundamental piece of the VFX pipeline, used by every single visual effects studio on the planet and counted by dozens on every film or tv show.
Sooner or later you would have to deal with lidar scans, that's why I have recorded this video, more than 3 hours of professional vfx training about how to use lidars scans.
In this video we will learn:
- What is lidar scanning.
- How we use lidars in VFX.
- How lidar technology works.
- Basics of working on-set with lidars.
- Lidar hardware.
- Lidar software.
- How to process point clouds.
- How to generate meshes for 3D work.
All the information on my Patreon feed.
Thanks!
Xuan.
Full photogrammetry pipeline in macOS? /
Nuke IBL templates /
Hello,
I just finished recording about 3 hours of content going through a couple of my Nuke IBL templates. The first one is all about cleaning up and artifacts removal. You know, how to get rid of chunky tripods, removing people from set and what not. I will explain to you a couple of ways of dealing with these issues, both in 2D and in 3D using the powerful Nuke's 3D system.
In the second template, I will guide you through the neutralization process, that includes both linearization and white balance. Some people knows this process as technical grading. A very important step that usually lighting supervisors or sequence supervisor deal with before starting to light any VFX shot.
Footage, scripts and other material will be available to you if you are supporting one of the tiers with downloadable material.
Thanks again for your support! and if you like my Patreon feed, please help me to spread the word, I would love to get at least 50 patrons, we are not that far away!
All the info on my Patreon feed.
Lighting checker Mono White /
Ricoh Theta for image acquisition in VFX /
This is a very quick overview of how I use my tiny Ricoh Theta for lighting acquisition in VFX. I always use one of my two traditional setups for capturing HDRI and bracketed textures but on top of that, I use a Theta as backup. Sometimes if I don't have enough room on-set I might only use a Theta, but this is not ideal.
There is no way to manually control this camera, shame! But using an iPhone app like Simple HDR at least you can do bracketing. Still can't control it, but it is something.
As always capturing any camera data, you will need a Macbeth chart.
For HDRI acquisition it is always extremely important to have good references for you lighting distribution, density, temperature, reflection and shadow. Spheres are a must.
For this particular exercise I'm using a Mini Manfrotto tripod to place my camera above 50cm from the ground aprox.
This is the equitectangular map that I got after merging 7 brackets generated automatically with the Theta. There are 2 major disadvantages if you compare this panorama with the ones you typically get using a traditional DSLR + fisheye setup.
- Poor resolution, artefacts and aberrations
- Poor dynamic range
I use HDR merge pro in Photoshop to merge my brackets. It is very fast and it actually works. But never use Photoshop to work with data images.
Once the panorama has been stitched, move to Nuke to neutralise it.
Start by neutralising the plate.
Linearization first, followed by white balance.
Copy the grading from the plate to the panorama.
Save the maps, go to Maya and create an IBL setup.
The dynamic range in the panorama is very low compared with what we would have if were using a traditional DSLR setup. This means that our key light is not going to work very well I'm afraid.
If we compare the CG against the plate, we can easily see that the sun is not working at all.
The best way to fix this issue at this point is going back to Nuke and remove the sun from the panorama. Then crop it and save it as a HDR texture to be mapped in a CG light.
Map the HDR texture to a area light in Maya and place it accordingly.
Now we should be able to match the key light much better.
Final render.
On-set tips: Creating high frequency detail /
In a previous post I mentioned the importance of having high frequency details whilst scanning assets on-set. Sometimes if we don't have that detail we can just create it. Actually sometimes this is the only way to capture volumes and surfaces efficiently, specially if the asset doesn't have any surface detail, like white objects for example.
If we are dealing with assets that are being used on set but won't appear in the final edit, it is probably that those assets are not painted at all. There is no need to spend resources on it, right? But we might need to scan those assets to create a virtual asset that will be ultimately used on screen.
As mentioned before, if we don't have enough surface detail it will be so difficult to scan assets using photogrammetry so, we need to create high frequency detail on our own way.
Let's say we need to create a virtual assets of this physical mask. It is completely plain, white, we don't see much detail on its surface. We can create high frequency detail just painting some dots, or placing small stickers across the surface.
In this particular case I'm using a regular DSLR + multi zoom lens. A tripod, a support for the mask and some washable paint. I prefer to use small round stickers because they create less artifacts in the scan, but I run out of them.
I created this support while ago to scan fruits and other organic assets.
The first thing I usually do (if the object is white) is covering the whole object with neutral gray paint. It is way more easy to balance the exposure photographing again gray than white.
Once the gray paint is dry I just paint small dots or place the round stickers to create high frequency detail. The smallest the better.
Once the material has been processed you should get a pretty decent scan. Probably an impossible task without creating all the high frequency detail first.
On-set tips: The importance of high frequency detail /
Quick tip here. Whenever possible use some kind of high frequency detail to capture references for your assets. In this scenario I'm scanning with photos this huge rock, with only 50 images and very bad conditions. Low lighting situation, shot hand-held, no tripod at all, very windy and raining.
Thanks to all the great high frequency detail on the surface of this rock the output is quite good to use as modeling reference, even to extract highly detailed displacement maps.
Notice in the image below that I'm using only 50 pictures. Not much you might say. But thanks to all the tiny detail the photogrammetry software does very well reconstructing the point cloud to generate the 3D model. There is a lot of information to find common points between photos.
The shooting pattern couldn't be more simple. Just one eight all around the subject. The alignment was completely successfully in Photoscan.
As you can see here, even with a small number of photos and not the best lighting conditions, the output is quite good.
I did an automatic retopology in Zbrush. I don't care much about the topology, this asset is not going to be animated at all. I just need a manageable topology to create a nice uv mapping and reproject all the fine detail in Zbrush and use it later as displacement map.
A few render tests.
Akromatic base /
As VFX artists we always need to place our color charts and lighting checkers (or practical spheres) somewhere on the ground while shooting bracketed images for panoramic HDRI creation. And we know that every single look-development and / or lighting artist is going to request at least all these references for their tasks back at the facility.
I'm tired of seeing my VFX peers working on set placing their lighting checkers and color charts on top of their backpacks or hard cases to make them visible on their HDRIs. In the best scenario they usually put the lighting checkers on a tripod with it's legs bended.
I've been using my own base to place my lighting checkers and all my workmates keep asking me about it, so it's time to make it available for all of you working on set on a daily basis.
The akromatic base is light, robust and made of high quality stainless steel. It is super simple to attach our lighting checkers to it and keep them safe and more important, visible in all your images. Moving all around the set with your lighting checkers and color charts from take to take is now simple, quick and safe.
The akromatic base is compatible with our lighting checkers "Mono" and "Twins".
HDRI shooting (quick guide) /
This is a quick introduction to HDRI shooting on set for visual effects projects.
If you want to go deeper on this topic please check my DT course here.
Equipment
This list below is a professional equipment for HDRI shooting. Good results can be achieved using amateur gear, don't necessary need to spend a lot of money for HDRI capturing, but the better equipment you own the easier, faster and better result you'll get. Obviously this gear is based on my taste.
- Lowepro Vertex 100 AW backpack
- Lowepro Flipside Sport 15L AW backpack
- Full frame digital DSLR (Nikon D800)
- Fish-eye lens (Nikkor 10.5mm)
- Multi purpose lens (Nikkor 28-300mm)
- Remote trigger
- Tripod
- Panoramic head (360 precision Atome or MK2)
- akromatic kit (grey ball, chrome ball, tripod plates)
- Lowepro Nova Sport 35L AW shoulder bag (for aromatic kit)
- Macbeth chart
- Material samples (plastic, metal, fabric, etc)
- Tape measurer
- Gaffer tape
- Additional tripod for akromatic kit
- Cleaning kit
- Knife
- Gloves
- iPad or laptop
- External hard drive
- CF memory cards
- Extra batteries
- Data cables
- Witness camera and/or second camera body for stills
All the equipment packed up. Try to keep everything small and tidy.
All your items should be easy to pick up.
Most important assets are: Camera body, fish-eye lens, multi purpose lens, tripod, nodal head, macbeth chart and lighting checkers.
Shooting checklist
- Full coverage of the scene (fish-eye shots)
- Backplates for look-development (including ground or floor)
- Macbeth chart for white balance
- Grey ball for lighting calibration
- Chrome ball for lighting orientation
- Basic scene measurements
- Material samples
- Individual HDR artificial lighting sources if required
Grey and chrome spheres, extremely important for lighting calibration.
Macbeth chart is necessary for white balance correction.
Before shooting
- Try to carry only the indispensable equipment. Leave cables and other stuff in the van, don’t carry extra weight on set.
- Set-up the camera, clean lenses, format memory cards, etc, before start shooting. Extra camera adjustments would be required at the moment of the shooting, but try to establish exposure, white balance and other settings before the action. Know you lighting conditions.
- Have more than one CF memory card with you all the time ready to be used.
- Have a small cleaning kit with you all the time.
- Plan the shoot: Write a shooting diagram with your own checklist, with the strategies that you would need to cover the whole thing, knowing the lighting conditions, etc.
- Try to plant your tripod where the action happens or where your 3D asset will be placed.
- Try to reduce the cleaning area. Don’t put anything on your feet or around the tripod, you will have to hand paint it out later in Nuke.
- When shooting backplates for look-dev use a wide lens, something around 24mm to 28mm and cover always more space, not only where the action occurs.
- When shooting textures for scene reconstruction always use a Macbeth chart and at least 3 exposures.
Methodology
- Plant the tripod where the action happens, stabilise it and level it
- Set manual focus
- Set white balance
- Set ISO
- Set raw+jpg
- Set apperture
- Metering exposure
- Set neutral exposure
- Read histogram and adjust neutral exposure if necessary
- Shot slate (operator name, location, date, time, project code name, etc)
- Set auto bracketing
- Shot 5 to 7 exposures with 3 stops difference covering the whole environment
- Place the aromatic kit where the tripod was placed, and take 3 exposures. Keep half of the grey sphere hit by the sun and half in shade.
- Place the Macbeth chart 1m away from tripod on the floor and take 3 exposures
- Take backplates and ground/floor texture references
- Shoot reference materials
- Write down measurements of the scene, specially if you are shooting interiors.
- If shooting artificial lights take HDR samples of each individual lighting source.
Final HDRI equirectangular panorama.
Exposures starting point
- Day light sun visible ISO 100 F22
- Day light sun hidden ISO 100 F16
- Cloudy ISO 320 F16
- Sunrise/Sunset ISO 100 F11
- Interior well lit ISO 320 F16
- Interior ambient bright ISO 320 F10
- Interior bad light ISO 640 F10
- Interior ambient dark ISO 640 F8
- Low light situation ISO 640 F5
That should be it for now, happy shooting :)
Base for shooting references /
I built this rotating base for shooting references for modeling and texturing purposes.
Seems to work pretty good with a wide range of sizes from small objects to people around 1.85 cm and 80 kg.
It has two diferent positions, for 8 shots (45 degrees) and 16 shots (22,5 degrees).
