The Key to Cleaner 3D Scans: Cross-Polarization
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- Опубліковано 27 чер 2024
- Today’s tutorial teaches you everything you need to know about Cross-Polarization. The necessary hardware/gear, and why it matters. It is absolutely essential if you’re trying to scan an object that has a very shiny/reflective surface. Taking a look at the renders in Unreal Engine 5, it doesn’t take long to see the vast difference between the two approaches, the cross-polarized result is FAR superior. The scans done in this tutorial were made with RealityCapture.
GET 50% off your purchase of 3500 PPI credits for RealityCapture using "WILLIAM50" as your discount code!
For more information on RealityCapture:
www.capturingreality.com
Important links:
Intro to RealityCapture to UE5 Workflow Video: • RealityCapture to UE5 ...
Scanning all sides of objects in Reality Capture: • How to 3D Scan All Sid...
MAJOR THANKS to Grzegorz Baran for his in-depth guides and insights on photogrammetry. Find his channel and video I referred to here:
Grzegorz Baran’s Cross-Polarization Explained: • Cross Polarisation Exp...
Grzegorz Baran’s Channel: / grzegorzbaranart
Necessary gear for Photogrammetry:
Flashes:
Godox AR400 Ring Flash: geni.us/83IB0V
Elinchrom ELB 500 TTL Duo: geni.us/ElinchromELB500
Polarizing Filters:
Tiffen Circular Polarizing Filter: geni.us/XB38L
Nikon Circular Polarizing Filter: geni.us/acILA1z
Ring Flash Polarizer: geni.us/FlashPolarize
Transmitters and Other:
ColorChecker Passport Photo II: geni.us/tUEDhx
Godox XT-16 Transmitter/Receiver Kit: geni.us/7icY2
Flash Sync Cable: geni.us/DlZ63
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/ williamfaucher
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---------------
Timestamps:
00:00 - Intro
01:00 - CapturingReality
01:30 - What is Cross-Polarization?
03:39 - Polarization Explanation
04:46 - Necessary Gear/Hardware
05:56 - Gear: Polarizers
07:49 - Gear: ColorChart
08:07 - Gear: Transmitters
08:53 - Assembling the Camera Rig
09:12 - Why do we need this?
10:21 - Important Steps Before Shooting
11:47 - Scanning
12:28 - Into RealityCapture
13:36 - Limitations of Cross-Polarization
14:53 - Conclusion & Thanks
--------Cameras and Gear Used To Film This Video ------
DISCLAIMER: This video/description contains affiliate links, which means that if you click on one of the product links, I’ll receive a small commission. As an Amazon Associate I earn from qualifying purchases. This helps support the channel and allows us to continue to make videos like this. Thank you for the support!
My Streaming / Recording Setup (How this Video was Recorded)
Nikon Z6II : geni.us/OPxBG
Sigma 35mm f/1.4 Art : geni.us/ByMa
Deity S-Mic 2 Shotgun Microphone: geni.us/ed6pyO
Aputure MC Pocket LED: geni.us/uVZNl
Godox LEDP 260c LED Panel: geni.us/OgidwX
Godox Parabolic Softbox : geni.us/oHZ2b9
Godox SL-60W Studio Light: geni.us/68wx
I really appreciate your step by step approach, this all feels so crystal clear
Wake up. Browse notifications.
William's video.
This is a good day!
Hahah you're too kind!
Amazing William! I have heard about cross-polarization for textures and 3d models generation for years but I had no idea that there was a pratical and affortable way of doing it. Thank you for your amazing work!
So timely! I've been working on a cross polarization setup recently.
I'm glad someone is finally sharing this. This is common practice for ingesting assets at most film studios.
Great video! Informative & fun to watch.
I'm really thankful I found your channel last year.
You always make videos when I am working on this exact task. Great timing and great info as always!
Omg! I can’t wait for glass photogrammetry! Every one of your vids is so valuable and stacked with information- thanks for all your instruction!
Great video. It's given me a lot to think about regarding my set-up and why I was having so much difficulty with my last scan project.
Thanks William, I do photogrammetry and I was looking for a big budget flash, I was interested in the godox but didn't find anywhere a showcase of how much strong it is until you have done it. Thank you very much, now I know that it is the better choice 😀 also for small object you can use a rotation table like the foldio 360 which will automatically rotate and shoot at a predefined angle, in my case I use 10° so 36pics for each circle. it speed up the workflow and makes it so much easier.
your insight in subject is so detailed I'm amazed
Thank you!
Yet another fantastic video Mr. Faucher!
Great to see you're so close to 100k subs! Congrats William!
Definitely saving this for later reference. Great content as always!
I can't find it anymore, but someone once had a blog about a capture setup that was very cool. If you use a point source light (small flash bulb) and reflect it off a parabolic mirror, you can get collimated light. I forget all the technical details, but if you have cross polarized collimated light and you know the relative angles between your light and camera, you can then work out the angle of reflection and get a reflection map. It may have used Brewster's angle, I can't remember. I think you can separate metal from dielectric using Brewster's angle.
That sound awesome, did a quick Google using “collimated light reflection map photography parabolic mirror” but I mostly got research papers. Please follow up if you find it again.
A second issue regarding the Polarization phenomenon is about the Angle we are shooting at a surface. Avoiding extreme angles (like 0 degrees: almost parallel or 90 degrees: looking down at the surface) shall give better results in cross polarizing. There is an exact angle which cancels out almost 100% of reflected light; the angle depends on the material of the reflective surface, i.e. the refractive index of that material. Varnish, oil, water have different indices, so the angle varies.
Superb tutorial. Thank you!
Great video and info! Thanks!
William you're awesome thank you! That's some nice looking gear, and the results are clear. Thanks for the techniques!
Hey William massive congratulations on hitting 100K subs! Well deserved, your content is always very useful and your channel is such an inspiration. Is it just me or is there an extra lens in your quiver in the background?
great video excellent information that was presented clearly and precisely
Really nice info William, thanks. Can't wait for the glass approach. I work with plastic bottles, and a couple months ago did try to see if I could use photogrammetry, but PET/HDPE/PP bottles have a lot of problems to overcome. glare, reflection, transparency, repetitive features(or none at all) you name it :D
Are you able to paint them for the scan?
I approve. Now if we could use these techniques to get a 'clearer picture' of the micro cosmos....
Excellent production. Thank you.
Wow. Really informative. Thank you.
Very good video William! Thanks :)
this is amazing!! thanks!!
excellent as always !!!!
Thanks for teaching me photogrammetry!
Great tutorial ... again! It looks like, you will hit the 100k follower barrier soon. Congrats to this in advance. You deserved it. Off-topic question: What benefits registered people will get, when they pay for a membership of your channel? Thank you so much William and please go on!
one of the best videos which I have seen lately! your channel is the only one to which I have clicked the notification bell on :D I have been thinking there are sprays which some shoe customizers use to make leather more matt. would a spray help also to get better results on scanning objects?
Excellent info , thanks
very useful info, thanks!
Brilliant!! Thank you so much.
awesome information as usual! thks
This is gold.
you do service public man..manny thanks! 👏👏
thaks so much .. awesome as always
awesome stuff dude ! keep it up please !
Thank you!
Very neat results! I had quite similiar results with a 50 € Tiffen circular polarizer 52mm filter, a 80€ godox flash, a 25 € diffuser and a 20€ sheet of polarized film.
Hi @jobim3d, I'm interested in get a cheaper flash rather than the AR400. Which one do you use? 😀😀 Thanks in advance!
Just recently started scanning with this setup as well! Gotta say though, the ringflash polarizer you suggest is godsent and I immediately put down an order. I DIY’d it with a polarizer filter and gaffer tape until now but this is much cleaner!
I’m interested to hear if you found a workaround to scan ‘multi-layered’ objects.. last week, I scanned a model wearing mesh garments and the results are problematic.
thank you . we miss you
majestic Tutorial as always William,! thanks I always wonredinrg waht hardware does Quixel team uses and now I know!
Thanks!!
True Grzegorz Baran movies learn me how to do my job. I recomend them every one who work with photogrammetry.
Absolutely, he's a gem!
I love this man 😎
dang this is awesome
THANKS
This is such a great presentation of the cross-polarization method for eliminating reflections.
I just wanted to mention that Polarization as an optical phenomenon can be exploited only on Non-Metallic surfaces.
This means that polarized light can not be fully or partially cancelled when we are dealing with metallic objects. Which are photogrammetry's worst "enemies".
That is why we use fine powder sprayed on metallic surfaces to eliminate all metallic reflections. We lose the albedo - which is kind of black-ish anyway on most of metallic surfaces.
I'm not sure if there is any other method out there for metallic or semi-metallic objects for photogrammetry/3D scanning.
Any ideas are welcome.
Again, thanks for your fantastic tutorials, William!
I'm looking forward to your video on reflective objects. I scan sailplanes, which are white, shiny plastic, and it's really difficult scanning them. Only works if the sailplane is really dirty!
Will this technique work correctly for face scan? Thx for the great content as always!
Yes.... ua-cam.com/video/rBwPGYBn0Tc/v-deo.html
just don't look in the flash or you can say goodbye to your eyesight
Great video. You explained everything clearly. I am totally new to 3d scan (but not in 3d) and I wanted to ask: Is the Godox flash (or any other similar flash) necessary or even usefull when you want to scan a small stone house? Lets say that you have ideal conditions, no sunlight, because it's an overcast day or because it is early in the morning. Will the light of the flash reach the house from 2-3 meters where you stand and shoot? Is it an overkill? What's your opinion?
This is awesome! Thank you for this
One question. Do you know what is the furthest distance for this setup when shooting an object?
Would it work on a house outdoors?
Again, your videos are the best - thx!
The image + color quality of your video is INSANE. Why are you doing this to us?
I hope you do something cool with UE5's new metahuman thing. How to light them nicely and maybe some animation tips. (I really like these videos even though I don't even use UE5 myself. The tech is just too cool :D)
Hello William! Can you please make some Niagara Particles tutorials? That would be nice!
Great video William. I’m curious, how would you approach taking pictures of the bottom of the shoe???
I've made a dedicated video on scanning the bottom sides of objects already, it's the one I recommend watching in this video! Check it out!
If you have to move closer / further from the subject, do you adjust your exposure? Or do you have your flash on TTL mode or something so it adjusts for you?
Very cool. How do you get a roughness map, or did you just use a constant value?
I guess you''ve got to photoshop the sh*t out of the baked texture :P
This is so brilliant William. Can’t wait for the video you teased, about scanning glassware etc! Btw can you say your last name slower next time - we all need to hear it. I keep saying “fockar” but I think you say “fow-shay”, ie. rhyming with cow slay?
Hahaha I've had a doctor call me Mr.Fucker once, wasn't even mad. It's pronounced "Foe-Shay". It's a french last name, super weird pronunciation :P
Great video! So the best is to cross both filters by 90° which is blocking most of the light when putting both filters on top of each other. Is this correct?
Great tutorial William! I am putting together this x-polarization setup and I am having difficulty synching the Godox AR400 with my Sony Alpha 7R through the flash synch cable. The flash fires after pressing the camera shutter. Could you provide any info? Thanks in advance.
For just one day, 8/4/22 the Flashpoint version of the Godox flash is on sale at Adorama for $319. It's apparently only available at that price through their email list. That's a great price.
I know im already 25, but will you be my father? :D Everybody needs his idol :D
I had no one driving my muse, no one supporting me, my mum was angry at me that im all time on PC ( doing 3D since my 13). And turning it off to get me out of home. And dad was beating the shit out of me cuz hes i dont know pathetic? .. Anyway, you are the person i would like to became one day. You are my idol. And thanks to you, my muse is always back. You make a new video, i watched and every second is so packed with information, watching you is like being a Musician student watching Mozart playing and explaining in the process. It gives you the dopamine rush promise, that if you go create with those new learned stuff, youll get rewarded. Thank you, and please dont stop. If people like you ever diss appear from the internet, i think i would continue.. i would give it 2 years and then i would burn out.
So, Thank you
Great tutorial! Thanks a lot!
Would be wonderful to see how you would approach a photogrammetry of a human head, a human hands and the full body.
I’m talking about single camera photogrammetry.
Thanks!
I probably wouldn’t do that with a single camera :P it WILL work, but even your subject moving just 1mm will mess up the alignment and won’t give you a clean scan. There’s a reason lightstages and multicamera scan setups are expensive :)
I've had great results scanning people using an iPhone with Lidar sensor and the Scaniverse app. I guess the sensor eliminates most of the error from the subject moving.
Awesome video, do you know if this setup will work on the Canon EOS rebel T7 that lacks the center pin on the hot shoe?
Yeah it'll work fine, just use the cable instead of the wireless transmitter! :) Assuming your camera has a 3.5mm headphone jack
Hey Will, do you think the Godox R200 would be plenty powerful enough as long as you're not doing photogrammetry outside in sunlight?
Will this also increase flat and straight metal parts, like for example gun parts? Would be interesting to see the Slide of a Pistol scanned with this technique. It would be awesome if Hard Surfaces wouldn´t become wobbly ;-)
The dude who invented that must be super smart!
nice
Could you make a video on how to build the ideal PC for unreal engine on a moderate budget between $2500-3500?
How large of a lens can you use with this? Would a lens that uses 82mm filters work? Thanks.
Great video and explanations. It would be interesting to see results side by side of ring flash with and without polarization. It seems like this is a comparison of ring flash polarization and ambient lighting. I also seem to find that Reality Capture will build geometry from some specular reflections based on surface geometry - so I think there can actually be some advantage to specular light. If I were capturing the binoculars, I would try bounced strobe lighting without cross-polarization.
wow! cross polarization makes the raw photos look like half life 2 when you turn lighting off!
woah
may be it out fo Topix, any plan to make totorial about road spline feature use method rvt, and combine with parallax?
Good suggestion!
How do you make roughness maps for these scans ?
Make a row with Cross polarisation and other without but use the flas. Then when you extract the texturas of the 3d model from the two tecnics use photoshop to subtract the albedo map with cross polarisation from the map without… et voi la… magic hapens!
Hello William, what Lens are you using for the scan with Nikon? Thanks.
Sigma 35mm f/1.4 Art
@@WilliamFaucher Thank so much.
Anyone know where to buy the Elinchrom rig?
Don't share all the Secrets 😉😏!!!
Joke aside, great Video !
shouldnt you first align the lens filter with the sunlight, then align the flash , to the lens filter, so it cuts both the sun and the flash highlights?
You can, that's why it's nice to have the option to rotate the filter. In general I don't recommend shooting in direct sunlight anyway, because the AR400 can't overpower it completely. Even an umbrella for shade will help.
A limitation you didn‘t talk about is the size of the object to scan right?
It‘s clearly visible in your photos that the flash light falls off quite rapidly the further away a surface is. The technique / hardware you‘re presenting here wouldn’t work for big objects right?
What dimensions would you recommend to use at max?
Of course falloff is something to take into consideration. But it depends on what you're scanning to be honest. I wouldn't scan a house like this. But I've seen people scan entire HUGE rock formations or entire patches of roads with a cross polarized approach. It all depends on what you're scanning and how your shots turn out. It is impossible for me to consider every possible scenario and give you a max dimension, because there really isn't one. It boils down to, try it and see :)
It's less of a limitation, and more about understanding how light works, the falloff is the Inverse Square law, which applies to any light.
Just think like this If you are fisicly able to be 1 - 2 meters of the object you want to scan all arround, no matter the size… it can be done… you dont need to cover all the object in the frame…
That makes sense, thanks for your replies! Would it also be somehow possible to shoot some frames without cross polarization from further away (capture the whole object in a frame) just for alignment. And somehow exclude those pictures in Reality Capture for mesh reconstruction and texture baking? or is that non-sense?
@@nicolasvondru8556 If you take photos at long distance, does will not make as detailed textures as the closest ones. Remember the best photogrametry relies on constant light, constant f-stop, and when possible constant distance from the obeject (same focus). In fact constant factor is more important than the quality of your rig. Please see how you can do it in this video: ua-cam.com/video/egJ78oxFaTU/v-deo.html
Can anyone answer me where to plug in the cable? I have a canon 90D camera. When I plug it in MIC or Headphone jack, the flash won't react at all.
Does cross-polarization also work on metallic reflections?
yes! but you’ll need to remove some purple/blue light in post
Hello,how did you find out exactly what Epic Team is using for photogrammetry ? Where can I find out this information?
Ive talked to them directly ☺️
And what about using flash with filter?
I bought a same Ring flash you ahowed.
Bought a circular polarization filter for my lens and a polarization film.
I don't have the 3D printed adapter for the flash yet.
Will it all be for nothing if I just tape on the polarization, if the film isn't completely flat?
Ordered a print of a free stl files I found online, just in case..
you dont need the polarization film, it comes with the frame from ScanSpace :)
I have the same rig too… i bought the filter from New Zeland, i am waiting more that 3 months…
@@WilliamFaucher Yes, but I don't have the frame, 200$ is a bit much for me, for that part. I just had it ordered from a 3D printing service for a fraction of the price. 15$ to print it. Should arrive in under a week, because it was printed locally. And I had bought the polarization film before.
any alternatives to Ring Flash Polarizer, they are out of stock
Hi William! I'm working with toys company which products are made most of plastic. Would you reccommend this solution for photogrametry of let's say... HotWheels cars or Barbie dolls? This might be very useful for me as a 3D artist!
yeah absolutely! Since both of those have shiny surfaces, cross polarization can help. Though plastic like barbie dolls might be hard to scan because they are featureless. But I'll make a video on that topic
@@WilliamFaucher Great news! I've seen there are plenty of sprays and powders for refletcive and shiny surfaces but that slows down the workflow.
Does it work on glass
when I use polarizer on ring flash and try to take pictures, it should remove all glare and reflection right ? but its blue color is showing up on object surface. trying to debug this problem but exactly dont know whats the issue.
totally normal. The polarizing film on the flash doesn’t polarize quiiiite everything. Some polarizing films do, but they burn and fall apart quickly. This one I use is way more durable and won’t burn away like most polarizing films. it’s easy to remove the blue in lightroom :)
@@WilliamFaucher thanks, waiting for a video on the reflective object and less feature point objects 3d scans.
Anyone know if this technique works on larger scans, such as Buildings? Outdoor Statues. i guess the flash wouldn't be strong enough on a large scale object. Maybe mid size would be fine.
Yeah I wouldn't recommend this on a large building, you'll never get even lighting, your best bet is to shoot on an overcast day!
What lense are you using?
Sigma 35mm f/1.4 Art
I wonder if there's a practical way to take 2 photos at alternate polarisation and then subtract the difference.
You can get a polarised filter and rotate it 90° but keeping the camera in the same place and repeating it enough times to get a scan is insanely impractical
Yes. This is how professional light stage scanning setups work.
For a static object/prop, you can do this manually as long as the light source and camera are not moved at all.
A sample of the result (on a face using a high speed professional light stage) is shown in Epic's Matrix Characters video: ua-cam.com/video/h_dJtk3BCyg/v-deo.html
Has anyone been able to get the Godox AR400 to work in high speed mode (eg. anything faster then
Is there a reason you need HSS/High Speed Sync? Bear in mind you will lose a lot of flash power output if you use that.
Did you ever make the video about scanning objects that are near featureless?
Yes! Sortof! My creating an arctic environment video that I posted a couple months ago :)
@@WilliamFaucher awesome. Love the content. Keep up the good work sir!
How to Render shadow catcher in unreal engine
Why isn’t possible to achieve the same result using two polarized lens filter rotated at different angles instead of one in the light and the other in the lens?
Because then the light itself isn’t polarized
did you say modular?
Hey William, what about Mobile Phone Hardware? Because more and more people are switching to a good mobile phone like an 15 pro max when shooting under good lighting conditions. Is there a cross pol setup for mobile phones? This would be curious! Can you make a video about it? Thanks in advance!
Hm. I am not aware of any specific setup for cross polarization on mobile, but the process is the same. Just need a light that is polarized and have a polarizing filter on your phone camera. But really by the time you’ve gotten a bunch of additional hardware for mobile usage, you might as well be using a proper camera. Phone cameras are pretty good, and there are apps like realityScan to do this kinda thing. But it’s no real substitute for a cheap dslr/mirrorless. If anything a phone costs 2-3x as much as a second hand camera these days.
@@WilliamFaucher Hey and thanks for the answer!
Maybe it would be worth a try!
I think in good light, which would be available, smartphone pictures from the slightly better smartphones are really good. There are now lots of comparisons between mirrorless cameras and the top smartphones on UA-cam.
I think I'm primarily interested in cost savings and mobility. The Godox Ringflash alone costs €500 and that doesn't include a polarizing filter! You always have your smartphone with you and the additional hardware would probably not be as disruptive as a professional setup.
@@autodriv3r405 the main issue with smartphones is that there is a TON of computation done on the images which negatively affect photogrammetry results. Nice looking photos does not equal good data for mesh generation. If you just want something quick and easy on the go and don't care too much about quality, go for it!
But if you are serious about getting good, clean results that don't need a ton of cleanup in post, I can't recommend the smartphone route. Gotta use the right tool for the job. You can probably use a small handy swiss army knife to do some bushcraft, but it will never replace an axe.
@@WilliamFaucher Ok i understand. I thought that you could take the smartphone results to a new level with additional hardware to save money and weight. If you then shoot in RAW and further optimize the images afterwards in a RAW converter....mhhh....but yeah, youre right. An axe is an axe, a pocket knife is a pocket knife...
I came up with the idea because the results from my sister's old camera, the EOS 700D, felt worse than the photos from my current 13 pro max. And the slow autofocus.....
@@autodriv3r405 The EOS might LOOK worse than your smartphone because your phone is doing a TON of computational work under the hood. Doing in-camera HDR, sharpening, contrast, saturation boosting, it is doing a LOT of hacks to make everything look prettier. But for 3d scanning, an image being pretty isn;t the point. We want to capture as much raw data as possible. Phones are really good, and I made a video about RealityScan ( a mobile app) which gave me pretty good results!
ua-cam.com/video/EiBCdtGSRAA/v-deo.html
But for any serious work I will be using my bigboi camera :)
indoor only Alienbee ABR800 Ring flash