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Topics - HMArnold

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General / How to tell if the GPU is being used
« on: October 13, 2023, 06:22:30 PM »
I have a RTX 3080TI and am running from SSD drives, latest Nidia and CUDA drivers. The GPU shows up correctly in the Agisoft "Preferences"

My alignment jobs always finish normally, but the GPU never gets above 5% and is usually at 2%.

Image attached

Is there anything else I'm supposed to do to utilize the GPU? Any way other than the Windows 11 "Performance" I should be looking to make sure it's being used?

Any suggestions appreciated

General / White Horizontal Lines On Orthophotos
« on: March 17, 2021, 02:21:04 PM »
Switching over to new computer, installed Metashape 1.7.2, testing with an old set of UAV images.

I get a set of very thin horizontal white lines across the resulting orthophotos, that seem to cut though vegetation in some places.  No lines in any of the source photos.

See attached image

I'm sure its something that's turned on be default that hasn't been before, but I can't seem to find how to disable them.

Any suggestions appreciated

General / DTM Tutorial
« on: April 18, 2016, 03:51:31 PM »
I'm trying to learn how to export a DTM from aerial images

There is a forum post that references a tutorial, but the link goes to the main Photoscan page.

Is there such a tutorial?



General / DEM Export Digits Of Accuracy
« on: February 08, 2016, 07:26:37 PM »

I'm trying the use DEM Export data to calculate volumes of enclosed structures.

My thinking was that if I break down the point cloud into discreet intervals where Lon was the X coordinate, Lat was the Y coordinate, and Altitude was the Z coordinate, I would be able to easily calculate volumes, differences between previous DEMs, etc.

When I work a dataflow using the highest possible settings I know of for each step and then export the DEM using the XYZ format, I still get some X/Y grids squares with no altitude values, even if I set the grid scale to 100mm.

The attached images show the location within the sample DEM of grid square that don't contain any dense cloud points. By averaging the nearby grid squares that do have altitude values, I can estimate the altitude of the missing info, which is what is shown in the images.

As you can see from the shapes, the grid square without cloud points is not random, but has a repeating consistency, which leads me to think it's coming from the data and/or underlying calculations in terms of the available digits of accuracy.

The export accuracy for XYZ DEMs seems to be 6 digits of accuracy, which could very well explain my problem because that would be a resolution of approximately 90mm for my latitude, so it's possible some grid squares could round/truncate out of existence completely.

I see in the "Export Points/ASCII PTS" format that the values have 7 digits of accuracy (example attached), which would bring me to about 9 mm of accuracy, but I don't see any way to export using that format in anything less than the entire point cloud in full resolution, which for the first workflow I tried turned out to be 1.5 gigabytes of text.

Here is my question :

Is there any way to get a DEM Export using the XYZ format with 7 digits of accuracy or conversely any way to control the export size of the ASCII PTS format without decreasing the resolution of the entire workflow process?

A work-around would be to write a program that sifts through the full ASCII PTS export calculating the average altitude for each grid square, bringing the volume down to a useable amount, which is what the DEM Export/XYZ process does, but before I start anything that requires working with 1.5 gigabyte text files I thought I'd ask.

Suggestions appreciated


General / UAV Volume Calculation
« on: February 02, 2016, 02:48:11 AM »
This is a long thank-you post to Agisoft Support.
I’ve been trying to create high resolution DEMs in order to calculate the internal volume of containment berms around oil storage tanks using images taken with a UAV.
The problem has been that although normal orthogonal (camera straight down) images will stitch in Photoscan and generate a DEM, they don’t detect and report variations in the top of the  structures well because of the triangulation problems associated with two overlapping images taken at almost the same angle, straight up.
On the other hand, if you fly the UAV lower and point the camera back towards the top of the structure being modeled, Photoscan will more accurately pick up altitude changes in the top of the structure, but flying a UAV mission that returns an image set where every picture will stitch is very difficult.
Usually, on a 4 sided rectangular containment berm, one or two of the sides will stitch, but on at least one side some or all of the images are left non-aligned.
The nice folks at Agisoft Support looked at a small subset of clear images with an overlap above 70 percent where one row was taken directly over the berm with the camera pointed straight down, then one row of images down each side with the camera pointed at 60 degrees down from horizontal.
They told me that the reason the images didn’t stitch was because the angle between the images was too great, and they suggested that 30 to 35 degrees was the most Photoscan could work with.
I went back and re-designed the autonomous UAV mission to take a vertical set, then a sideways set from 30 degrees from horizontal, and the images stitched properly every time.
Then I went back and added two more legs down each side at 60 degrees from horizontal and found that now they would align reliably.
Because they took the time to look at my images and make an informed response, they saved me days of work trying to adjust the overlap and distances, all of which would have been a waste of time.
The other thing I learned was that including the camera orientation values from the mission flight log helped Photoscan tremendously in terms of properly aligning all images.
For these missions I used a DJI Phantom 3 Pro, and by calculating the camera direction (YAW) and camera vertical angle (GIMBAL PITCH), I was able to set the accuracy values for all images to 1, and I have yet to have a non-aligned camera, even when I include the images taken during the turns at the end of each leg.
The DJI Phantom 3 Pro also includes worthless altitude information in the EXIF data associated with each image, that they call “GPS Altitude”. I have read that the GPS Altitude tends to be inaccurate, but with DJI, it’s more than that. I live near the coast and I have yet to export a single mission of images where the altitude values in the EXIF data were above sea level.
For my platforms sold in the US, DJI also writes the GPS altitude in feet, which using the WGS 84 coordinate system, Photoscan takes as meters. That means that all the alignment angles are off, and Photoscan starts properly disregarding the altitude values. This causes some cameras to be positioned below the ground, up in the sky, whatever.
By using the flight log data you can create a Reference/Import file that overwrites the incorrect DJI altitude value with a more rational “Mission Altitude” value, which is referenced from the take-off home point and seems to be very reliable.
The trick with Photoscan is that you can’t just import camera orientation values.
If you’re going to import anything, then as far as I can tell, you have to import everything.
That means you also have to calculate the lat/lon values for each image based upon it’s EXIF time, even though the flight log info doesn’t correspond to individual images, it writes a record every few milliseconds.
It is possible and I’ll help anyone interested if I can
Thanks Agisoft, for a great product and informed support


General / Ortho Photo has disjointed structures - 90% overlap
« on: December 14, 2015, 08:02:36 PM »
I'm attaching the image overlap page from the report from a recent UAV flight where the report shows a 90% overlap on the central images (I think), but any structure on the ground that has a vertical component gets cut up and shows as a disjointed mess.

It doesn't seem like increasing the overlap would do much good, is there a solution other than flying higher and taking few images, with an associated decrease in effective resolution?


General / Photos That Don't Align - Helpful Trick
« on: December 11, 2015, 05:22:14 PM »
I was having problems with some sections of photos not aligning in a group, but they would if taken separately.

I went through the whole chunks method and had a lot of trouble getting the chunks to align properly at the end.

After not getting any responses on the forum, I asked the support email folks

They told me that if you uncheck all the photos that aligned properly, then check all the ones that didn't, and run "Align Photos" again, it doesn't erase what you had before, it just tries again to align those same photos with the existing group.

It worked great for me and I have used it several times now

No idea how you would know where to find that in a manual

General / Vertical Entities On 3D Models
« on: December 10, 2015, 10:33:02 PM »
If there is already a post on this, please tell me the search term to use.

On several structures I have imaged with a UAV, I get a very good rendering of the structure from the sides and above, but I get vertical entities that connect hanging structures to the ground.

There are many images that show there is nothing there, and background structures are clearly evident.

I'm attaching an example showing the rendering with the entities and an actual image from roughly the same angle.

Is there a setting or solution to prevent these entities?

Thanks in advance

General / Chunk Alignment - Photogrammetric Images
« on: November 18, 2015, 12:58:59 AM »
I have been using Photoscan for a while now to combine images from a UAV into mosaic images.

Most of my projects can be done in a single chunk, but one appears to be too large because if I break the images into 3 sections, each section aligns fine (Attachments 1, 2, 3), but if I try them all together there are gaps in the camera positions that align.

The project is an agricultural field that doesn't vary in altitude by more than 2 feet over the entire area, and the images all contain altitude values that don't vary by more than a few inches.

When I align and create a mesh for each individual chunk, everything appears normal.

When I try to align the chunks using "point based" and include all three chunks, I don't get a viewable result after several hours of processing.

When I try to align the chunks using "camera based" the chunks appear to be aligned at one end of the field, but at the other there are significant altitude differences, as shown in the attached "merged chunks" screenshot.

I have also tried extending the range of each chuck so that there are some overlapping images across chunk boundaries.

Is there any way to get the alignment process to use the image altitudes properly?

Suggestions appreciated

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