Hello,
so, I'm an archaeologist by trade, and we're (generally speaking) sort of technology bottom-feeders, so my apologies for the lack of familiarity with what seems like should be a straightforward situation.
I have a 5.4mm replacement lens on a 3+ Silver and it works extremely well:
http://peauproductions.com/store/index.php?main_page=product_info&cPath=124_126_127&products_id=685
I've noticed jello/chop on video in 15+ mph wind, but the stills I've gotten at 0.5s interval look great.
I'm running into problems understanding the specs though, or at least how to use them to:
- create camera calibrations for Photoscan and Pix4D
- create a custom camera profile xml for 3DRServices/Tower
I know how to create and place an xml so that Tower recognizes it *as detailed elsewhere on this site), and I know how to do camera calibrations for Photoscan and Pix4D, but I don't really understand what's going on with the specs and how to convert them.
Performing a 3D Calibration with Pix4D, tells me the focal length of the new lens om the GoPro is "2.6333", as opposed to the stock which reads as 2.77. I'm ashamed to admit, I would have expected that number to be 5.4, but I know there's a relationship between the 5.44mm and the f/2.5 that I'm not getting.
To further complicate things, the camera profile .xml for 3DR/Tower looks like this:
gopro%20silver%203%20stock.xml
At the end of the day, I'd really like to know:
- In Photoscan and Pix4D, do I change the "focal" length to 2.633 (as calculated) rather than 5.44, (which is what I originally assumed, but now think is wrong)
- I don't have the faintest idea why the 3DR/Tower xml focal length value is set to 14 for a stock GoPro, but what on earth would I want to set it to based on the Peau replacement lens?
thanks for any insights anyone might have the time to provide!
Replies
Huh - so whatever is going on with Photoscan, it seems to be working OK.
Yesterday, I reflew a structure scan that just was not working well.
Here's the medium resolution (for alignment, cloud, and mesh):
https://drive.google.com/file/d/0B4GwYrFMW6TPRW9aLVg5RlZOMUk/view?u...
There are obviously some errors in there, but for a first pass with no masking or cleanup, I was really pleasantly surprised.
BTW - one thing I've noticed that I think may have made a huge difference. I changed my flight speed on both waypoint and circle modes to about 1/2 the original speed.
Whether it's an issue with a stock GoPro or the replacement lens, I was definitely getting motion blur at full speed, knocking that down makes a huge difference in image quality! That scan was about 5 minutes of flight time at 1/2-speed.
Hoping the high quality version will turn out similarly, but it's going to take a day or two with my computer...
I am using a silver 4 with the same questions. I have been getting a focal length error in Pix4d with 104% Can you post your setting you have for tower and what you are using for pix4d.
Thanks
Hi - so I am still trying to figure out what's going on with Photoscan, PhotoModeler, and Pix4d results, but I did look at the camera parameters here:
https://github.com/ne0fhyk/3DRServices/tree/master/Android/assets/C...
and double check the sensor size (though yours will be different on the 4 I think), then changed the focal length to 5.4mm, which seems to work perfectly in Tower (attached).
In case you hadn't already found this:
https://github.com/DroidPlanner/Tower/issues/1420
It's instructions for where to put the custom xml
GPSilver3_5_4mm.xml
Huh - so whatever is going on with Photoscan, it seems to be working OK.
Yesterday, I reflew a structure scan that just was not working well.
Here's the medium resolution (for alignment, cloud, and mesh):
https://drive.google.com/file/d/0B4GwYrFMW6TPRW9aLVg5RlZOMUk/view?u...
(NOTE: you need save the PDF locally and then zoom out, I also hadn't setup scale in PhotoScan when I saved it since it was a rough cut)
There are obviously some errors in there, but for a first pass with no masking or cleanup, I was really pleasantly surprised.
BTW - one thing I've noticed that I think probably made a difference: I changed my flight speed on both waypoint and circle modes to about 1/2 the original speed.
Whether it's an issue with a stock GoPro or the replacement lens, I was definitely getting motion blur at full speed - knocking that down makes a huge difference in image quality! That scan was about 5 minutes of flight time at 1/2-speed.
Hoping the high quality version will turn out similarly, but it's going to take a day or two with my computer...