Agisoft Metashape
Agisoft Metashape => General => Topic started by: JMR on October 21, 2014, 02:00:14 AM
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Yes, believe me! wonderfull cameras most senses, they're great for terrestrial job. but DON'T EVER put on board of a UAV, just trust me. Don't waste your money. It took me a while to understand why because photos looked beautifully sharp, but even sharpness can hide the worst evil.
Kind regards
GEOBIT
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Hope you're going to give us a bit more info than just that.
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in a Lumix GM1 the total exposure takes 1/25s depite you set speed to something as high as 1/4000... it uses electronic shutter for any S numbert over 1/500.
Look at the first image, it seems all decent... but hides enormous random distortions due to camera movements (shot at s1600, f4)
the second shows what you get at the same speed (*)
Beside this, the camera is all ways lovable: built-in time-lapse, almost ridiculously small, reasonably light and very good sensor rendition... if you are not flying and things stay steady.
Kind regards,
GEOBIT
(*) source http://m43photo.blogspot.com.es/2013/03/gh3-electronic-shutter.html (http://m43photo.blogspot.com.es/2013/03/gh3-electronic-shutter.html).)
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Ahhh Gotcha. I forgot about the electronic shutter
Can you avoid using the electronic shutter or is 1/500 not fast enough.
Perhaps the E-PM2 would be a better option. Not much larger, but with a mechanical shutter to 1/4000.
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Could somebody explain what is the problem with electronic shutter for aerial photography ?
I've seen many critics related to GoPro's shutter system, but honestly, I don't understand how it can interfere with photogrammetry priciples.
I saw some geometric distorsions on close range photos of fast moving objects, but not really on aerial photso.
Geometric distortions related to superwide angle lens is another story, of course.
I'm also using a Lumix GM1, and while I'm quite impressed by the image quality in "normal " photos, photogrammetric processing is quite disappointing. Could this be related to the electronic shutter ?
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LX100 has a mechanical shutter up to 1/4,000 sec based on it's specs:
http://www.panasonic.com/uk/consumer/cameras-camcorders/lumix-digital-cameras---point-and-shoot/compact-cameras/dmc-lx100.specs.html
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:-X It seems You are right. Ive changed the title. :-[
I read the maximum was 16000 and asumed that the new lx100 shared GM1 shutter (sorry, Panasonic)
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Could somebody explain what is the problem with electronic shutter for aerial photography ?
I've seen many critics related to GoPro's shutter system, but honestly, I don't understand how it can interfere with photogrammetry priciples.
Electronic shutter means the sensor reading is done line by line. So, even though at pixel level, exposure may be very short (1/1600), the whole photo takes a while to be read, as much as 1/25seconds... that's ages!
Lets say you fly at 10m/s (fast for a copter but rather slowish for a plane), a photo that takes 1/25 s starts to be exposed at a point P and capture is finished 40cm ahead. Each pixel is excited for short time so the photo may look sharp, but the geometry is compressed along flight path if sensor readout rolls upwards... but the case is actually worse because the flight path is not a perfect line nor the speed is constant, and aircraft vibrations cause geometry ripples... the result is that photogrammetry principles are basically destroyed.
I got pixel errors for reprojections bigger than 14 pix for some markers that look perfect! the ground control error is 16 centimeters while the GSD is 4 milimeters. That's a nonsense!
I did the very same flight project one month ago just before excavations, with the very same lens but with an Olympus EPM1. It gave 0.15 pixel, and 0.009 m for ground control error... pretty decent.
After the flight with the GM1, the archaeologycal findings were covered with geo-textile and filled with sand to prevent damage and unwanted "visitors" during this winter. This was done inmediately after the flight and having photos briefly checked at my order "OK, surveying done, start closing the site"... but actually the survey done is a crap and I can't heal it by no means.
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Thank you very much for these very clear explanations !
Do you think using GM1 with the "normal" shutter (at 1/500) will be OK ? I really appreciate the compactness of this camera, and the performance of the Panasonic 14mm pancake seems rather good on "ground" photos.
The build-in intervallometer is also a great advantage for aerial photography, even if the impossibility to use it together with wifi tethering is a major drawback.
Based on your experience in your field of application, which camera will you recommend with the following specs:
- very compact (has to be used on a small UAV)
- with good wide angle prime lens (eq. 28 mm)
- with external power supply (I use it also for multi-hours missions on a "manned" helicopter)
- remote trigger (can be wired) and intervallometer. Full tethering will be a plus
- built-in GPS is also not mandatory, but certainly useful
I don't think there are many possibilities on the market.
Sony NEX7, Pana GX7, Ricoh GR ? any other ?
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olympus-pen-e-pl7. Wifi. timelapse, excelent sensor... and very easy to hack trigger by wire
GR is a very good option but is not as flexible as an interchangeable lens one (http://www.four-thirds.org/en/microft/lens_chart.html (http://www.four-thirds.org/en/microft/lens_chart.html))
Pana GX7 is excelent but heavier and bigger than Oly...
External power needs to be hacked too for the Oly as there is no oficial external power adaptor.
micro zd 12mm f2.0 and 17mm f1.8 are better choices than than the Panasonic 14mm, Panasonic 20 is also much better than 14mm whose only advantage is lightness.
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Agree on Olympus, but like to add, that E-PL5 is also excelent and cheaper option. You can use newer 25 mm f1.8 lens.
And there is no need for wire trigger hacks as a trigger cable with video out exists. :)
As for the external power supply you can search for DC couplers, but was not able to find one for Oly except DIY page : http://weirdologic.blogspot.com/2014/01/dc-power-to-olympus-pen-camera-diy.html
I guess a Nikon Coolpix A II could be interesting if it will be any faster than current version.
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having a timelapse function is a basic requirement, but we have to be very careful with the actual specs:
- some cameras have a limitation in the maximum number of photos that can be included in a sequence
- some cameras have limitation in the minimum interval between photos (10 sec with Canon's EOS utility tethering system...)
I need a system allowing for up to 1 sec interval (ideally, I would like to define the interval in decimal seconds, e.g. 1.7 second)
and no limit to the number of recorded images (the limit being defined by the capacity of the SD card: on GM1, I can capture 7100 images)
Do you know what are the specs of the built-in timelapse function of Oly PL7, Ricoh GR, Nikon and Sony ?
I will have a look to the suggested solutions for external power supply, but I know it's not a trivial issue.
I use for very long time a custom 12V-7.2V adapter for my Canon EOS cameras, connected to a motorbike battery. Works perfectly.
I tried to do the same with GM1, but it was more sensible to power stability, and I have to use a 12V to 220V convertor and the original Panasonic DC coupler (220V-7.2V) , but this solution is less efficient.
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Dear Nadar: do not consider built-in timelapse your basic requirement that simply. You can make any camera timelapse capable by means of a post-stamp sized electronics. Buy any camera that can be triggered by wire and invest your money in the best lens you can afford.
Olympus cameras have very important advantages:
1. their multifunctional port has live view out and trigger input in one, so it is easy to hack a cable supporting both functionalities (video can be transmited)
2. screen will be turned off automatically once you plug the connector in (reducing consumption considerably)
3. 4/3 crop lenses are smaller than apsc and today this sensor size is not a handicap anymore.
4. There are a lot of lenses available with m4/3 mount natively and even more with adapters
5. battery shape is very easy to copy, so to make coupler. A voltage regulator can be used to power the camera on a s3-lipo for a day if you want.
here you are your programmable time-lapse with no limitations and many extra features built in. (it also can be powered by the same li-po) http://vp-systems.eu/camremote.html (http://vp-systems.eu/camremote.html)
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Fully agree with your recomendations², especially about the importance of the lens on the global performance.
My choice of GM1 + Lumix 14mm/ 1:2.5 was mainly dictated by the size and weight.
Olympus PL7 seems fine, and your proposed solution for timelaps is OK with me;
The biggest pending issue (IMHO) is with power supply:
"5. battery shape is very easy to copy, so to make coupler. A voltage regulator can be used to power the camera on a s3-lipo for a day if you want."
Are you sure it is so simple ? On some cameras, you can't operate if the battery compartiment door is not closed, and if don't like too much the idea of drilling a hole or cutting a corner of the cover. Canon EOS cameras have a very clever design: a small rubber part that can be pushed away to insert a wire in the battery compartiment.
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I don't know about E-PL7, but E-PL5 works with battery doors open. As for the power source I don't know as I didn't test it jet. It's just an article I found. I use E-PL5 on my multirotors and have no need for the extended power, but if I need it, I will test it.
For the timelapse a StratoSnapper 2 is also a nice solution and a bit cheaper too. ;)
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using your E-PL5, how many pictures can you get on a fully charged battery ?
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Using the E-M1 or E-M5, I've had no issues getting over 1000 shots from a single battery. I also just checked the E-M1 and it will work with the battery door open.
With the Olympus cameras, the main issue with batteries is how long the camera is running, rather than the amount of photos taken.
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Yes, I have checked recent job and have made little less than 800 shots without any battery issues. Never tested max shots as with multirotor I am limited with it's autonomy :)
As JMR wrote, when you use video out cable, the LCD of the camera turns off and as it is the main power consumer ( flash is excluded ), you get quite decent working time.
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I have 2 types of projects: one type is based on using UAV, and for this one, I agree, the battery life of the camera is clearly not the bottleneck (I have about 10 minutes of safe flight. acquiring photos @ 1 sec interval corresponds to about 600 picture).
The second type of mission is done with manned fixed wing aircraft or helicopter. On these mission, I fly a few hours (up to 7 hours). I'm not acquiring photos during the whole flight, but the camera is mounted outside of the aircraft, and I don't have direct access to it, so it has to be in standby mode at the begin of the mission, and allow for remotely controlled capture when we arrive on the area of interest.
A mission can involve a few thousand pictures (on the Lumix GM1, I can store 7100 JPG images on the 64 Gb SD card)
That's the reson why a definetely need an external power supply.
Another question to experts:
Do you know a camera allowing for fast acquisition (say 1-2 second interval) of long sequences (say 100 images) in RAW mode rather than JPG ? On my EOS 600D, I can acquire about 10 images in fast sequence, then the buffer is full and the acquisition becomes sluggish.
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1-2 seconds isn't very fast. I'd have thought that would be inside most cameras time lapse settings.
Just had a look on my E-M1, and it will do 999 shots at 1 second interval.
If I turn on burst mode and shoot at 3 frames per second, then I get around 220 (raw) frames before the buffer fills up. (Keep in mind the E-M1 has an insane buffer compared to most other cameras).
If I shoot at 10FPS then I get the usual buffer count of 44 odd raw images.
On my older E-M5 I get 30 odd raw frames at 3fps.
Both of these (and I suspect most similar cameras) appear to be unlimited at 1FPS.
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ricoh gr or sigma dp or olympus pen E-PL5 or 7 what is the best for UAV
The weight is very important and the distance with the obect is never more than 200 meter
thanks fot your responds
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Does anybody knows if the new Panasonic DMC-GM5 has the same speed for the mechanical shutter than GM1 (i.e. max 1/500 sec) ?