Messages

1

General / Re: What are the implications of using GCPs as manual tie points without coordinates

« on: March 29, 2024, 02:02:47 AM »

I have just been informed that the key element in structure from motion is the automatic detection of tie points, some 4000 of them per overlap, and therefore there is no need for manual tie points.

2

General / What are the implications of using GCPs as manual tie points without coordinates

« on: March 29, 2024, 01:01:43 AM »

Hi there,
 
On my latest project I laid out GCPs and surveyed them, however, incorrect settings were used in my base station so my coordinates are wrong. I know I can still use my GCPs without coordinates as tie points to provide relative accuracy, but I do not fully understand the implications. Can anyone describe what these might be? For example, would using GCPs without coordinates provide the same quality orthomosaic, but just have no georeferencing?

Thanks.

3

General / Does Agisoft factor in vertical and horizontal error from imported GCPs?

« on: February 09, 2024, 08:22:52 PM »

I have an elevation model and I am wondering the best way to report the accuracy. In the processing report Agisoft provides estimates of horizontal and vertical error but I am wondering if that includes potential error from my GNSS. When I import GCPs into Agisoft, I include the vertical and horizontal accuracy as reported by my GNSS receiver. I am assuming that the final processing report would consider this information when estimating accuracy, but just wanted to make sure.

Cheers

4

General / Reference/Generic Preselection for UAV imagery

« on: December 11, 2021, 07:19:57 PM »

Hello,

I have been reading a lot about the Align Photos settings but wanted to get some advice on which settings are best to use for high resolution UAV imagery flying over vegetated areas. My sensors are the DJI P1 and Micasense Altum.

The P1 images will have PPK run on them so their coordinate information will be very accurate. The Altum images won't have PPK run on them but still have coordinate information within the images, just not as accurate. My questions are:

- Should I run reference preselection and generic preselection on the P1 images, or just reference preselection? I read in the manual that using reference preselection without generic preselection might be best for aerial surveys of forested areas, which pertains to my study area.

- Should I run reference preselection for my Altum images with the less accurate coordinates? Or generic preselection, or nothing?

If anyone has advice on the other settings (key points, tie points, guided image matching, etc.) and what would be best for UAVs flying over vegetated areas that would be appreciated as well, but I may make a new post for those parameters.

Thanks,

Ben

5

General / Camera Calibration for DJI P1

« on: November 17, 2021, 11:42:11 PM »

I am a bit confused about camera calibrations. Should I be running a camera (or lens) calibration on my DJI P1 before processing images? In a photogrammetry course I took a while ago, I took checkerboard images with my phone camera and used those to calibrate the camera but I don't really know how that would apply with my P1.

Thanks,

Ben

6

General / Orthomosaic compression for image classification

« on: November 09, 2021, 02:45:04 AM »

Does exporting an orthomosaic with an LZW compression impact things like image classification? I am assuming I should export an uncompressed orthomosaic but my file sizes are extremely large and in some cases it would be nice to use a compressed version.

Thanks,

Ben

7

General / PPK data import

« on: November 04, 2021, 10:58:02 PM »

I have a dataset of DJI P1 images that I just ran through PPK software and I was wondering if there were any steps I need to take to make sure Agisoft is using that info.
From what I can tell, you would click on the "Import reference from exif" button in Agisoft, but I just wanted to clarify if this was the right process?

Thanks,

Ben

8

General / Importing a geoid into Agisoft

« on: July 08, 2021, 06:11:43 PM »

Does a geoid need to be in tiff format in order to input it into Agisoft? I have an HT2 2002 geoid in .BYN and .GGF format that I need to get into Agisoft but I can't figure out how to convert them to tiff.

I found this webpage: https://www.agisoft.com/downloads/geoids/ which has a bunch of geoids for download, but the one I need isn't in there. The HT2 2002 geoid is a Canadian Model.