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Topics - DayGeckoArt

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Feature Requests / Request ability to change default settings
« on: July 11, 2023, 07:12:12 AM »
Every time I create as project, I have to go to the Camera Calibration menu and set Rolling Shutter to "Regular". It would be very helpful to allow this and many other settings to be changed permanently so that we don't have to set them every time. This setting in particular seems strange to force virtually every user to change it every time, because almost everyone needs rolling shutter compensation.

General / How to reload photos?
« on: May 07, 2023, 09:22:11 PM »
I use raw drone photos and edit them in Lightroom. Sometimes I re-edit further and I used to be able to just replace the photos in the project folder and the Agisoft would read them. For example, I just edited a set to increase brightness and bring up shadows. But with the current version, the program doesn't use the new photos for building the orthomosaic. It seems to be using a cached version somewhere. Is there a way to force Agisoft Metashape Pro to re-read the edited photos and use those to build the orthomosaic?

General / Flying manually and rolling shutter compensation
« on: January 29, 2023, 09:40:24 PM »
I fly my DJI Air 2S and DJI Mini 3 manually, and I try to get all my photos while the drone is moving forward. But sometimes I accidentally take a picture while the drone is stationary. Or I intentionally take  some photos with the drone stationary to get some different angles on a particular building or natural feature. Do I need to split these photos into a separate group so they don't get rolling shutter compensation applied?

General / How to use GPS/INS Offset settings
« on: September 25, 2022, 05:56:04 AM »
I've searched and read the manual and I can't find anything clear. My DJI Air 2S drone usually has wildly inaccurate elevation data, possibly because of the datum it's using. Usually it's about 75 meters below where it should be. For example when I take a photo at ground level at 5 meters elevation, the value in the exif data is -70 meters.

How do I adjust this in Camera Calibration? According the manual it seems like I would put in -75 but that seems backward. Should I put in +75 to add 75 to the exif value?

General / How to upload 3D models or point clouds?
« on: May 29, 2022, 10:17:12 PM »
I've tried the built in uploaders in Agisoft Metashape and none seems to work. I get either garbage models, they don't get displayed at all, or error messages. I've tried meshes, point clouds, and in both geographic and local coordinate systems. The closest I've gotten is Cesium but it attemps to display a point cloud with a large square for each point

General / How to rotate mesh or point cloud?
« on: May 27, 2022, 08:10:05 AM »
I converted a model from WGS84 to local meters, and the whole thing ended up rotated at a weird angle instead of keeping the original XYZ orientation. I can't find any way to rotate the whole point cloud or mesh. It seems like it should be straightforward but the manual has nothing, I can't find any button or menu option. How do I rotate everything? I'm not looking to rotate the view or the region

General / Which Optimize Camera Alignment Parameters should we use?
« on: April 16, 2022, 10:20:28 PM »
The manual says what the different checkboxes mean on the Optimize Camera Alignment dialogue, but doesn't explain when or why you would use each one. The last 3 are disabled by default, but I've seen user made tutorial videos where they check all but without an explanation. I usually check all except the Advanced boxes, when I optimize alignment after adjusting my GCP markers. Is this correct? Or should I be using the default settings? Does it depend on the type of camera?

I've been doing GIS for about 15 years and majored in geography. Since I first started looking into photogrammetry I've been wondering why ground control points are exclusively considered to be square targets that you put on the ground. In GIS we usually georeference aerial photos, scanned maps, etc using existing imagery to find features on the ground.

Well over the past month have been using Agisoft Metashape Pro trial to learn drone photogrammetry. Previously I had only generated simple orthophotos using Maps Made Easy and Pix4D

I work at Maui County where we have access to high resolution orthophotos from Pictometry. In Hawai'i we also have a pretty extensive set of LiDAR data for coastal areas and with the full state coming later this year. Both are available to the public through ArcGIS Online which is good because I'm doing this as a personal project. Since I don't have access to a high precision PPK GPS receiver, or access to some of the places I wanted to map, I decided to try using the Pictometry and LidAR as a source for GCPs

The first landscape I've mapped is a heiau (Hawaiian shrine or temple) on a small knoll here on Maui. It's preserved but surrounded by development. The landscape that provides context for the heiau is almost completely altered and soon buildings will be blocking the viewsheds, and even oblique drone views, so I needed to collect photos ASAP. I went out around solar noon on a few weekends and manually collected raw photos with my Parrot Anafi drone. Some were in cloudy weather so I separated sunny/cloudy into separate projects. I applied Colorchecker profiles in Lightroom except for the set of JPEGs I got with Pix4D Capture (I don't recommend this program, it collected distortion corrected images and all with different white balance and exposures)

I found a set of features on the landscape that are visible on Pictometry and my drone photos, mostly electric company concrete pads and manholes. I found coordinates by placing features in ArcGIS Pro and calculating latitude/longitude in WGS84. I then grabbed elevations from the closest LiDAR points. Many of the LiDAR elevations aren't totally accurate because they were collected before construction of the infrastructure but I think they're close enough

I didn't use all of these GCPs, I tried to choose ones that were widely spaced from each other just like we do when georeferencing flat maps

For the sunny weather project I used 521 photos to generate the model, from many different elevations and angles, but only the low altitude (25m) for generating textures and orthomosaics

The orthophoto from Agisoft matches Pictometry almost exactly, which is what you'd expect. I can't say how accurate it is, but it would be the accuracy of the imagery plus whatever error is introduced in the georeferencing process. I believe the Pictometry rating is "below 1 meter" but it varies with location. More importantly, the orthophoto and 3D model match an existing reference set of imagery that is standard for government and related uses in Hawai'i, and future orthophotos will match the existing ones allowing direct comparison. Also, since Pictometry is already orthorectified, any error should just be simple shift, so future adjustment will be easy!

Another orthophoto from the cloudy weather project:

I think this is the power of a 3D model... Our brains can really understand a landscape if we can see a 3D model. A photo from a drone is a view from one vantage point and has perspective distortion. Viewing from the ground is even less helpful. I learned only from looking at my model that the lot is already built up much higher than the two knolls, so the mansions will tower above. I'm not sure this development would have been approved if the community could see and understand the landscape in three dimensions

I learned a lot in the past few weeks, but I only have 6 days left on my trial, so in a week I'll have to switch to another program that I can afford. Unfortunately there is no product from Agisoft that lets someone like me do this kind of non-commercial mapping :( I hope they consider some kind of home use or hobby license. The standard license is fine for objects but without geographic capability it's not useful for documenting landscapes

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