Topics

1

General / GCPs and accurate reconstruction accuracy estimate

« on: January 03, 2023, 11:35:39 AM »

Hello

On how many pictures in the dataset must you mark the control points to get the most accurate estimate of the reconstruction accuracy of the model?

I have a model that I need to reconstruct with a mean error of less than 1.8 cm. To get the most accurate report of the error should I mark the control points in all of the images where they are visible or should I leave only those that were automatically detected with the Detect Markers function?

This question has been probably been asked a million times already but for the life of me, I cannot find a satisfactory answer.

Thanks for your help and insight.

2

General / Hardware and specs for an ideal processing server

« on: September 06, 2022, 01:08:39 PM »

Hello

I'm currently working on a project (purely theoretical) to build the ideal work server or HPC for the photogrammic workflow. From image processing to photogrammetry itself to rendering and creating assets and such.
I'm interested in the ideal hardware specifications for a machine like this. I've read some articles but none talk about an HPC configuration for such a use case and with Metashape workflow in mind.
My question is, what should I focus more when building such a machine? GPU or CPU processing power, RAM and storage sizes and so on. The projects running on the machine would be large, 20 000 images and more, running simultaneously.

3

General / Depth maps generation explanation

« on: August 30, 2021, 12:46:48 AM »

Hello

I'm currently puzzled as to how depth maps are generated and filtered. This is from the manual:

"Depth maps are calculated for the overlapping image pairs considering their relative exterior and interior orientation
parameters estimated with bundle adjustment. Multiple pairwise depth maps generated for each camera
are merged together into a combined depth map, using excessive information in the overlapping regions to
filter wrong depth measurements."

How do the levels in the GUI come into play here as in what do they mean?
And how is the depth map filtered? What is this excessive information that is used?

I would welcome an explanation.

4

General / Advantages and disadvantages of Depth Map and Dense Cloud model generation

« on: July 29, 2021, 06:58:23 PM »

Hello

I'm currently researching the advantages and disadvantages of generating meshes from Depth Maps and Dense Clouds. My findings from trial and error are as follows.
Overall, the Depth map is a superior method of generating meshes when a large enough set of photos is available.  It creates a more detailed mesh with less noise and processing time and skips the dense cloud generating step.
The Dense Cloud method is better when a smaller sample of images is available but creates a noisier, less detailed mesh.

I was wondering if there is a detailed documentation or use case for when to use one method or the other. I couldn't find anything useful on my own.

5

General / Error when building UV for object

« on: July 15, 2021, 09:20:54 AM »

When building UV map for an object, I get an error saying "invalid vector<T> subscript". I'm building 4 8k textures for this object. If I lower the count of those textures, the problem dissapears. Any way to avoid or solve this issues without lowering the quanitity of textures? UV mapping mode is generic.

Thanks for your help

6

General / Low quality (part of a) texture

« on: July 06, 2021, 04:01:21 PM »

When texturing an object, a blurry low quality patch of texture appears in the middle of an otherwise high quality texture.

The images used are not blurry and the camears are perfectly aligned.
The object itself has about 12 milion poligons. The preset for texturing is in the attachments as well as a picture of the described problem.

This is not the only object i'm currently working on that has this problem.

Any help would be appriciated.

7

General / Looking for papers about the process of photogrammetry

« on: June 23, 2021, 10:15:53 PM »

Hello

I'm currently in the process of writing my thesis which is about the use of photogrammetry in cultural heritage.
I'm looking for any papers, websites, and publications that explain the process of photogrammetry with the use of 2D images (not laser scans) in detail.

Any help would be appreciated 

Thanks

8

General / Bad model from laser scan dense cloud

« on: April 26, 2021, 10:53:41 AM »

Hello

I'm trying to create a model from a dense cloud that was made with a laser scanner. I exported a part of the dense cloud into Cloud Compare to calculate the normals since Metashape doesn't calculate them facing inside as I want. The cloud has about 55.000.000 points which should be sufficient. I then set the bounding box to cover only part of the cloud from which I want to generate my mesh. The generated model comes out full of holes and noise.
I use the default settings in the mesh generation process and set the face count to high (which is about 11.000.000). 

Any idea as to why this happens and how could I fix this?

9

General / Generated model from laser data (dense cloud) is broken

« on: April 12, 2021, 11:17:41 AM »

Hello

I generated a model from a dense cloud, generated with a laser scan. The model should be highly accurate but instead, I got a broken mess. Any ideas as to why this happened? Screenshots of the model and the dense cloud are in the attachments.

Thank you for your help

10

Python and Java API / Extrude geometry between points

« on: February 25, 2021, 05:58:01 PM »

I want to raise certain parts of geometry, between 2 points on an already existing model.

For example, I have a rough scan of the environment in which I would, with this script, like to raise geometry (or possibly even add geometry) to a certain height to form a type of wall from point A to point B.

11

Python and Java API / Export Dense Clouds by Label

« on: February 24, 2021, 01:56:40 PM »

Hello

I would like to export only specific / selected dense clouds from a chunk with multiple dense clouds.
It seems that chunk.exportPoints() doesn't allow for specific dense clouds to be exported or am I missing something?

Thank you for your help.

12

Python and Java API / Exported LAS file error, File Signature not b'LASF'

« on: February 22, 2021, 08:02:26 PM »

Hello

I am trying to read an exported LAS file in python with PYLAS but I get an error saying: "Error: File Signature (b'<?xm') is not b'LASF'"

I am using this code to export the dense cloud as LAS file:

Code: [Select]

chunk.exportPoints(path=projectPath + tempFileName,
                       source_data=Metashape.DenseCloudData,
                       save_normals=True,
                       save_colors=True,
                       save_classes=True,
                       save_confidence=True,
                       format=Metashape.PointsFormatLAS
                       )and this bit to read the file:

Code: [Select]

las = pylas.read(projectPath+projectFile)
I only get this error from files exported in Metashape ( my current version is v1.7.1 build 11797). I have tried manual export with the default settings but to no avail. If I read a file I downloaded from the internet for testing, it works without problems.

What could be the problem here?
Thank you for your help.

13

Python and Java API / Changing the confidence of points in dense cloud

« on: February 11, 2021, 07:48:22 PM »

Is it possible to loop through points in a dense cloud and assign them custom confidence values?
I have looked through the Metashape Python reference and I didn't spot anything that would lead me to believe that this is possible.

Thank you for your answers