HANDHELD photogrammetry, high ISO, AI denoise... Doable/Advisable...?
polycounter lvl 9
Hello, is doing photogrammetry with Handheld Mirrorless DSLR (Cannon EOS M200), handheld, high ISO (800 lets say) and using newest AI denoise in Lightroom Classic possible...? Like will it look good? NO tripod involved (thus the need for high ISO setting in order to get at least 1/100s+ shutter speeds to hopefully NOT get blurry images) ...?
SO... i was thinking of getting a 2nd camera (Cannon EOS M200), PURELY for the purpose of "photogrammetry on the go" - to have a camera with me whenever i leave home for the city/outside. Its a smaller camera, so i can have it always with me and if i see something worth scanning (or just shooting for texture purposes) i will pull out the camera and "handheld" scan it... No more telling myself - "Oh... this is nice... ill come later back here with my Nikon and tripod and scan it"... Guess what - i NEVER DID, and thus "lost" the model/scan opportunity... (Few times I tried using a cheap smartphone i always have on me , but the scans are just not good...)
My question is: Is it worth it...? Like will the resulting scans be any good and more or less comparable with my nikon D3200 tripod scans...? Cause with the Cannon EOS M200 i will have to shoot without tripod (and even monopod), just handheld... Can you get a good looking scan handheld with such mirrorless camera...? Depending on the lighting, i will have to probably take majority of shoots with ISO 800, F8-F11, in order to prevent blurry images due to handholding the camera... I should be able to get at least shutter speeds of 1/100 sec and higher (1/125 etc.)... This should be enough to prevent blury images right...? I will denoise the high (800) ISO in lightroom classic using the newest AI denoise feature...
So could it be done, will the final scan be "any good" and comparable/ more or less the same quality as if done with a tripod...?
(will use agisoft metashape probably for the photogrammetry)
OR... can i shoot in full sun now these days? It was adviced that you should do scanning in shadow or when the sky is cloudy to get even lighting on your model... This is what i have always done, the downside is that there is LESS light entering the camera in these conditions, so you have to use tripod or high ISO settings... OR... did the "delighting" technology got so good over the years (i started 3d scanning like in 2015 or 2017 (?)), that you can now scan in full sun and auto remove the shadows later on with specialized tech ( i know agisoft metashape has some delighiting tools (2 seperate i think), Unity has some delighting tools, and there are probably others)... Did the delighting got so good over the years, that you can now shoot in full sun?
Replies
For this sort of work, I would recommend a Micro Four Thirds camera. Olympus' IBIS in particular is highly effective. Something like a used EM5 III is a good buy these days. These cameras have smaller sensors than APS-C and FF cameras, which means reduced dynamic range and increased high ISO noise. However, you will generally want to stop the lens down to make sure your object is in focus, so this negates the advantage of larger sensors. For instance, If you needed to use F16 on FF, that means F11 on APS-C and F8 on M43. This would mean using, for instance, ISO 3200, 1600, and 800 respectively. With the effective IBIS you might be able to get away with even lower ISOs.
Generally yes, you should still shoot with overcast lighting if you can. Shooting in bright sun will mean high lighting contrast that will be more difficult to process.
Compare the Sony A7 III to an Olympus EM5 III. At the same ISO setting the A7 III will have significantly less noise. However, if you need to stop down to F16 on the A7, you may need to use ISO 6400. On the EM5 III you can use F8 for the same DOF and use ISO 1600. At these ISOs, the noise levels will be roughly the same. If you used ISO 1600 on the A7, you would need to use F8 and your subject may no longer be sufficiently in focus - and you could use F4 and ISO 400 on the Olympus if the DOF was wide enough for your subject - again equalizing the noise performance.
Here's a comparison showing M43, APS-C (Canon) and FF (Sony) cameras vs your Nikon D3200. I've chosen equivalent ISO settings - the settings you would use to get the same DOF on all the cameras. You can see for the Oly, Canon, and Sony, the noise level is roughly equivalent. They're all better than the Nikon because it's very old and has a relatively inefficient sensor.
The larger sensor will only provide less noise if you are not light-limited and can shoot at F16 and the base ISO of the camera, which would be ISO 100 for the A7. This will provide the best dynamic range, best colors, and lowest noise. The problem then is that you need a lot of light, so you will need to either provide your own light source (not generally possible for photogrammetry in the wild, but you can create a studio lighting setup for smaller objects) or use a tripod and a long shutter speed.
Since you intend to shoot handheld on overcast days, the larger sensor provides essentially no benefits. The camera and lenses will cost much and be larger and heavier. If you have some other use for the camera (like low light action/sports/event photography) it may make sense to opt for a bigger sensor.
Re: sharper images. Generally, this is complicated, but it depends on both the quality of the lens and the resolution of the sensor. Certainly, with a 61 megapixel Sony A7r IV and a high-quality lens, you will get sharper images than you would with a 20mp Olympus EM5. But compare the EM5 to the 24mp Canon M200, the resolution is nearly the same and the quality of the lens you put on either camera (plus how stable you can make it) will make a bigger difference in the sharpness of the final image.
Re: turning off IS. I'm not sure where you've read that IS shouldn't be used or what the rationale for that recommendation is. It is commonly recommended to turn off IS systems if the camera is mounted on a tripod, so if you're reading a guide that assumes you'll be using a tripod, that would be sensible advice. But for handheld shooting, IBIS is extremely useful for all types of photography, especially if you're shooting in poor lighting conditions and trying to minimize noise.
As far as optical IS vs IBIS goes, optical IS is generally better than no IS and may be fine for your purposes. That said, IBIS systems can correct for more axes - Olympus' system accounts for 5 axes. It's not possible to correct for some types of movement (like roll, which happens when you press the shutter button) with optical systems. So IBIS will generally outperform OIS. There are systems that can combine OIS and IBIS as well, though only with a few specific lenses.
Modern IBIS systems are pretty incredible. With wider lenses, I can hand-hold my EM5 III down to shutter speeds of about 4 seconds. I wouldn't go anywhere near this long for photogrammetry, but it's a good example of how effective these systems can be. Generally, the IBIS systems in Micro Four Thirds cameras are the best, because the sensors are smaller so the system doesn't have to work as hard to compensate for motion.
Lastly, I would strongly advise getting a camera with a viewfinder. Holding the camera up to your eye can improve the stability of the system and up your chances of getting sharp images.
If you're not able to use IS I would recommend a shutter speed higher than 1/100, maybe 1/200 or so to minimize camera shake. This depends on the focal length of your lens too, for wide lenses you can use a slower shutter speed. The general rule is 1/focal length (35mm equiv), so with a 50mm lens (35mm on APS-C, 25mm on M43) you would want 1/50, but I would double or quadruple that because you're looking for critically sharp images (rather than "good enough" for small prints and low-res web images). You could also shoot a burst of 3 and pick the sharpest (usually the middle exposure is the best), but that's potentially a lot of extra sorting work.
"I think you mean 1/4 of a second?" No, I mean 4s. Olympus's first-gen 5-axis IBIS was good for about 0.5-1s with wide-angle lenses. The more recent cameras can push it quite a bit more. You have to hold the camera reasonably steady to go that low of course. But it's great because you can do long exposures for things like waterfalls without having to bring a tripod with you on hikes. I'm not suggesting you drag the shutter that low for photogrammetry work, but it's a good example of how effective these systems are.
So I would guess the software has some tolerance for these types of things. But I haven't done extensive testing, so I can't say for sure.