Topics

1

General / Tips and tricks for creating the highest quality/most efficient ortho image?

« on: June 27, 2023, 02:13:01 AM »

Im looking to create a new video on how to make the best possible ortho image from UAV photogrammetry, In terms of efficiency and quality.




I was hoping to get some input here from this fine community if anyone has any tips and tricks I can add to the list of parameters I am going to test.




I have an idea on what the answer is to most of the following questions but was hoping to get opinions of others, and then do some testing to hopefully get a somewhat definitive answer.




How much motion blur can you have before it affects quality? 2x GSD, 4x GSD?

At what point does shadowing become too significant an issue?

Does more overlap at a higher altitude help with stitching elevated objects such as powerlines and tall buildings?

Does more overlap improve quality? What is the minimum overlap required for a typical (non homogenous) area of interest?

Do obliques images help?

Does creating your DEM from depth makes make a difference?

Are there any processing settings that make a significant difference (blending mode, refine seamlines, hole filling, ghost filtering, ect)?

Can you create an acceptable ortho without any Nadir images?

What effect does changing your f-stop have? What is the best f-stop to use? And in what situation?

How much effect does changing your iso have? Can I get away with iso 200, 400 in low light conditions without significant quality loss?





If you can think of any other questions you'd like an answer to or to have some testing done, please add them here.

2

General / How are you using the meshes you create?

« on: April 22, 2023, 09:11:14 PM »

You've scanned a outdoor scene, processed the data, cleaned it, now what? How are you/your client finding value in that mesh? How are you/they using it?

3

General / Best way to get a mesh into Autocad?

« on: April 10, 2023, 04:15:12 AM »

What is your workflow for getting georeferenced objects (parts of a mesh) out of Agisoft and into Autocad?

4

General / Cleaning your sparse cloud via gradual selection

« on: April 03, 2023, 06:41:33 AM »

I've been experimenting cleaning my sparse cloud with gradual selection using the techniques listed is the following USGS handbook (https://pubs.usgs.gov/of/2021/1039/ofr20211039.pdf)

However after significantly cleaning up the sparse cloud and removing a large number of bad points, once I create my dense cloud it is almost identical to the dense cloud I created by not cleaning the sparse cloud.

Has anyone else observed this? Is it a waste of time and effort to clean the sparse cloud?

5

General / Techniques to clean your point cloud in Metashape

« on: March 26, 2023, 01:25:30 AM »

Im curious as what techniques is the community using to clean data inside of Agisoft?

So far im using;

• Filter by confidence
• Gradual Selection - Reprojection error
• Gradual Selection - Projection accuracy
• Gradual Selection - Reconstruction Uncertainty

Does anyone remove some photos via estimate image quality and pull out any below X value?

Any tips to generally improve my point cloud processing results that can be done in program?

6

General / Aligning photos, optimizing cameras and gcps - HELP PLEASE

« on: March 18, 2023, 05:02:29 AM »

I’m trying to run some tests on accuracy with X number of GCPs and seeing weird results.

100 acre sites. 16 GCPs set with rtk. 800 images taken with a M3E running rtk.

Test 1 - rtk only, gcps used as checks. An average error or 2cm hz and 2cm vert.

Then I did what I thought would negate the rtk positions of the images, i unchecked every box in the reference pane beside the images and picked my GCPs the way I normally would, optimized cameras with the images unchecked and the GCPs checked and reprocessed. I didn’t realign images, I was under the assumption that when I pressed optimize cameras based on the new settings it would not use the rtk positions anymore. I saw slightly better results, nothing unexpected yet. But as I ran the project over and over taking away gcps, reoptimizing and reprocessing I wasn’t losing as much accuracy as I thought. Even at 3 gcps only. So I realigned as well with 3 gcps set as control and the rest as check and still had only a few cm off error across the site.

Could the rtk positioning of the images be making its way into the processing results somehow and tightening everything up?

7

General / Geoid Not Being Applied

« on: March 14, 2023, 11:28:28 PM »

I have images that were captured in WGS84 (RTK) and I would like to convert them to NAD83 UTM11N with a CGVD23 (HTv2.0 Geoid).

When I choose convert to "NAD83(CSRS) / UTM zone 11N" I can see there is no vertical datum applied to that map projection. I have the option to convert to  "NAD83(CSRS) / UTM zone 11N + CGVD2013 height" but we don't really use CGVD2013 here.

I tried that option anyways knowing my local shift is 0.30m and it came it 0.60m out of position so something weird is going on there too.

I can shift my finished point cloud in NAD83(CSRS) / UTM zone 11N by the CGVD28 geoid separation in CloudCompare and it works out ok but its not really the right way to do it because I'm shifting ellipsoid elevations. On this site the geoid separation changes by about 30mm from one end to the other.

My current work around was to shift the CGVD2013 converted cloud. It's still not right but the best I have right now. The geoids match up relatively well over small areas.

Does anyone know how I can apply the Geoid I want to apply? I have it in my Geoid folder already, I just need to figure out how I can apply it. Ideally I could tell Agisoft that X geoid should belong to Y map projection.

8

General / Importing RTK images

« on: March 12, 2023, 06:28:03 AM »

When I try to import images taken from my M3E that was capturing images in RTK mode it isn't importing camera location accuracy even though that box is checked in preferences.

Is there something I need to do to the images before importing them via Workflow > Add Folder ?

9

General / Optimizing Processing Time?

« on: March 04, 2023, 09:24:35 PM »

I recently discovered the benefits from processing my point cloud using higher quality settings when constructing my point clouds. However I would like to increase the time it take to process.

I have a dedicated workstation I use for my photogrammetry processing with the following specs;

NVIDIA GeForce GTX 1070
i7 - 7700 CPU @ 3.60GHz
64.0 GB of Ram
Windows 10

I'm fairly ignorant when it comes with computer hardware and have two questions.

1. How can I make sure Agisoft is using what I have to the fullest to ensure the fastest processing time possible?
2. What would my best "bang for my buck" be to increase processing time? Ex. A better video card, more RAM, ect.

My recent project took 3 days 19 hours for depth maps generation time and 2 days 4 hours for dense cloud generation time. Would it be possible to get both of these combined under 24 hours without spending $1000 and retaining the quality?

10

General / Measuring on model outside of photoscan

« on: February 15, 2019, 05:55:40 AM »

What's the easiest way I can have my clients be able to take measurements directly on my 3d model? I tried to import it into Google Earth as a KMZ but the ruler snaps behind my model to the surface of the earth. I tried sketchfab but my model wouldn't load in the distance progra.

11

General / What deliverables are you providing your client?

« on: February 05, 2019, 08:04:17 PM »

I've been a surveyor for about 15 years now and over the last year I've been doing aerial surveys with a p4p and photoscan. My deliverables include:

An .las point cloud
Georeferanced orthophoto
A flythrough with my model inserted into Google Earth
And a photoscan error report

I'm interested in hearing if anyone is giving their client anything different?

12

General / Exporting a DEM in RGB?

« on: February 03, 2019, 10:36:03 PM »

Hello all,

I would like to export my georeferanced DEM and bring it into civil 3d so I can view it the exact same way I view my Ortho. Is this possible? If not, can I just export it exactly as I see it in photoscan into a PDF so I can send it to my clients? I basically want a visual deliverable of the DEM.

13

General / 3D Printing

« on: November 12, 2018, 03:33:54 AM »

I work for a design company and we've been hired to design a vineyard based on existing ground. We've flown the bare earth and created a civil 3D surface from the .las and that is what I'm using for my designing. However I would like to 3D print the existing ground and also the design fields plotted on the existing ground. The issue is when I "extract solids from surface" it limits me to 100,000 triangles which isnt detailed enough for my 500 acre site. And when I try to export a .STL of my 3d model directly from photoscan it comes out very blocky. Any suggestions?

14

General / Best way to measure linear features

« on: March 21, 2018, 08:54:30 AM »

Im doing an accuracy comparison and need to measure the sides of these houses the best possible way using my point cloud/model to compare with what I've measured them as with a total station & Disto.

There are some holes in the point cloud, I have to make due with the data I have. The method I do i upload the model to sketchfab and its measure tool to make the measurement. But my model is pretty choppy (processed on high). Can anyone recommend a better method or way to clean up my model a bit?

Thank you

15

General / Large Error in GCPs

« on: February 13, 2018, 12:19:05 AM »

Im working on a thesis project for my bachelors in Geomatics where I compare the accuracy and suitability of UAV surveying vs traditional methods. Im using a phantom 4 pro and Nikon D5300 with a 35mm prime lens

I took over 900 images on my 26 acre site. 300+ nadir images, 300+ in a oblique grid pattern, 150 in a oblique circular pattern and around 100 with a ground based dslr (at face level and elevated 3m on a painters pole).

My first chunk (nadir images) processed very nicely. I had 11 GCPs, I used 2 as check shots. Everything is in a local coordinates system (UTM10 but without the scale factor as my GCPs were shot in with a total station). 333/334 images aligned, control point error = 0.003m Check point error = 0.028m

I used this for my DEM and Orthophoto as it has been my experience I get a better ortho from nadir images only.

My second chunk (oblique grid, circular photos and terrestrial photos) initially wouldn't align well with reference mode due to the fact my circular photos had bad elevation metadata. So I aligned using the disabled option and 611/632 images aligned which I was happy with. Everything looked good when I turned the camera positions on. I built a dense cloud with mild filtering and was very happy with the results so I proceeded to input my GCPs. When I was finished and optimized my alignment I now had huge (35m) GCP error and now when I view my cameras, it is a total mess. I dont believe I did anything different and now cant figure out what my next step should be to find the issue.

I am using this methodology and settings (http://www.agisoft.com/index.php?id=31)

Any suggestions on where to start would be greatly appreciated.