Topics

1

General / Zero resolution error when I try to create ortho

« on: May 09, 2023, 08:45:12 PM »

Hi

I have problems with my DEM (not a very regular surface). In the resulting ortho, straight lines that are on the surface of the object  are no straight (they have small "waves") that are clearly the result of DEM.

I exported the DEM (I call it original DEM) and I used QGis to smooth the DEM.

I imported the new DEM and when I try to generate the orthomosaic I got an Zero Resolution error.

I made a test which was to import the original DEM and the same happens (Zero Resolution error).

I work with local coordinates
Version 1.8.4

Need help
Thank you

2

General / Markers accuracy

« on: July 12, 2019, 12:28:55 PM »

Hello

I'm creating the ortomosaique of the roof of a factory.

I'm using ground control points (markers). I have access to a plant floor plan from where I got the coordinates from points that where in the corners.
In the photos I see the roof and its corners. I know the roof is "outside" the walls. There will be differences of several centimetres or even decimetres between both points (a corner at the ground level and the same corner at the roof level) and I don't have any possibility of knowing what is the difference.

I also suspect that the plant floor is not very accurate (there might be decimetre errors): as a surveyor that cuts my heart.

The orto that I want to create won't be placed on any referenced information. Only the orientation and scale are important.

So my strategy is to attribute to one point (the origin) very high accuracy (1mm) and less accuracy to the other points.

Concerning these I also have two ideas: one is to set the accuracy to 0.5m to all points; the other will be to divide the points in two groups: those that are nearer the origin will have one accuracy; the ones further will have comparatively less accuracy. The methodology is because of error propagation.

Any comments, further ideas, results from similar situations will be welcomed.

Kind regards

Maria Henriques

3

General / merged point cloud (natural+artificial) doesn't create DEM from artificial area

« on: July 12, 2019, 12:08:56 PM »

Hello

I made a photo survey of the roof of a factory.

1. Some areas are almost white and, for this reason, there are few tie points. The DEM that is generated has gross errors. The flat white areas have holes in it. This is natural taking into account the large areas (some square meters) of the point cloud without points.

So my idea was to create the point cloud of those areas. Because they have regular shape format based in vertical triangles and from the point cloud is possible to get the  coordinates of important points to generate the roofs, I recreated some of the white roofs and merged it with the natural point cloud (made it in Cloudcompare).

So I have a mixed point cloud: some areas have points from Metashape (natural points), others have calculated points (artificial). The DEM created by Cloudcompare is very logic, it makes sense.

In Metashape I delete the point cloud generated, and I import the new point cloud. When I generate the DEM I realize that it uses only the natural points. The area with artificial points (a point every 10cm) is blurred like it has no points to create the DEM.

I tried to solve: classify all the points as ground; I verify if the cloud was inside the region; I inverted the normals; in Cloudcompare I recoloured the cloud to a unique colour. No results

Need help

Kind regards

Maria Henriques

4

General / Input GCP image coordinates in Agisoft from Micmac image coordinates

« on: January 27, 2019, 10:00:03 PM »

Hi

During the creation of georeferenced points clouds from photos, is necessary to locate GCP (ground control points) in the photos.

I have access to a xml file that was created by Micmac softwares that has the location of the GCP in the photos (coordinates of the GCP in the photos = photo coordinates).

I've also seen that Agisoft creates a xml file that includes (with different tags) those photo coordinates.

If I change my Micmac xml file (the one that has the photo coordinates) into a xml file with Agisoft formats would it be possible to execute Agisoft and provide to this software information so it uses this xml file? How to do this?

Kind regards

Maria Henriques