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Messages - toxicmag

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76
General / Orthomosaic // discrepancy between markers in PointCloud
« on: March 16, 2017, 12:13:57 PM »
Dear users,

i'm building an orthophoto of a buidling facade and i'm using a local coordinate system for that.
Everything is fine, but when it comes to buidling the orthomosaic (using the specific projection pane for each side of the building) there is a shift of all the marker positions.

It's fine in pointcloud view and also mesh, so it must be some mistake in projection.

Type is "planar" and surface is mesh. Blending mode Mosaic.


Any ideas?   :/

Thanks

Alex

77
General / Cleaning point clouds // define field of view; line of view
« on: March 15, 2017, 12:20:13 PM »
Dear PS-user,

how do you deal with complex point clouds of i.e. buildings with facades and roof?
From top view the buidling is shaped like a "U" and on top the roof as well.

To get a nice mesh it is necessary to clean the point cloud, especially at all the windows and other reflections.

But besides Agisoft PS being a little weak in handling big point cloud data smoothly there is also the problem that you always have points of other parts of the building in view.

To delete and clean the points of the facade for example it would be great to define a "line of view". So you could "blank out" the rooftop for example and edit the facades points. By setting this "line of view" you could easily go through the whole project and clean up your point cloud.

Later again you simply go back to your standard view and all points are visible again and ready for meshing.

What do you think about it? Any solutions that are available right now?

Greetings

Alex

78
General / Meaning of errors in report // GeoMapping
« on: December 12, 2016, 05:58:36 PM »
Dear community,

do you know what is the exact description and definition of the error values which show the accuracy of the GCP in the final report?

To what is X, Y, Z related to as an offset?
The pointcloud?
The average above all photos and their GCP positions?

And what about the value in the last column?
0.405 pix should be definitely smaller than 2 cm....

I know that the topic is roughly described in the manual, but for GCP it says for example: "Error (m) - root mean square error for X, Y, Z coordinates for a GCP location"....

But related to what?

Thanks a lot.

Alex

PS: Example below.

79
Bug Reports / Coordinate System Conversion => theory and practice
« on: December 08, 2016, 03:27:42 PM »
Dear Support-Team and Users,

i experienced an error in the conversion of the coordinate systems.

Many of my clients in Germany still use the oldfashioned Gauss-Krueger-Format for their GCPs.
My aerial footage stores UTM positions in the photos EXIFs.

I was working on a site which is ~100m above sea level. My flying altitude was 100m and so the correct positioning of my EXIF data is at 200m for each photo.

To base this data on the same system i converted to Gauss-Krueger according to the EPSG-code my client is using (31467) and by definition the projection for Gauss-Krueger is based on a Geoid and the height-value is ~49m lower. So my flying altitude now is at 151m - at least the position of the photos.

This is not correct and does not match with the GCPs of my client which were recorded in Gauss-Krueger and the height value on ground-level is also 100m in their system. So when i imported their GCPs into my pre-processed model based on my EXIF data, their GCPs all were "floating" in 50m height.

I experimented with the "ground altitude (m)" in the Reference Settings Dialog but without any solution.


80
General / Re: Dealing with water - best way to edit mesh quantitatively?
« on: November 28, 2016, 04:49:37 PM »
Hello andyroo,

i found your post a couple of years later...  :D

What was your solution those days?


Greetings

Alex

81
General / geomapping and water reflections
« on: November 28, 2016, 03:07:22 PM »
Hello Photoscan Community,

how do you deal with reflecting water-surfaces while geomapping?

I'd like to map bigger piles of sand which are surrounded by water (river, lake etc.) and are moved from one location to another to have a kind of monitoring of the sand movements.

Reflecting surfaces do not result in proper points and so i masked the water area in every photo. It is clear that i have no points in this parts of the modell to compare one mapping with the following one.

What do you suggest in that case?

Thanks a lot.

Alex

82
General / Accuracy of pointcloud // geoMapping 30acres without RTK/PPK
« on: November 08, 2016, 10:44:59 PM »
Dear colleagues,

i got very good results in precisly and manually georeferencing my 153 photos with Geosetter.

Though not using any RTK/PPK solution at all the accuracy of the point cloud seems to be good.
I measured distances within the dense point cloud and they match reality quite well.

Since global accuracy is not needed for the project i can go with the inner accuracy only.

Can you help me out with ansering these two questions:

1) What inner accuracy can one expect from this process?
2) If RTK would be used the global accuracy will be higher of course. But will also be inner accuracy within the points be better?

Here's some report data related to that flight:

Number of images: 153
Flying altitude: 95.6 m
Ground resolution: 1.74 cm/pix
Coverage area: 0.121 km²

Camera stations: 153
Tie points: 253,623
Projections: 1,430,764
Reprojection error: 1.27 pix

Camera Locations:
X error (m)  Y error (m)    Z error (m)     XY error (m)       Total error (m)
1.64238        0.841022       0.656978         1.84519               1.95866

DEM:
Resolution: 6.95 cm/pix
Point density: 207 points/m²

Thanks for your support.

Alex

83
General / Re: 3D model (mesh) export // reduce to points only?
« on: November 07, 2016, 10:40:55 PM »
Hey Alexey,

sorry for the late reply.

The loss of coordinates of course was my fault.
Stupidly chose wrong system for export.   ;D

But question2 still is open. It would be a good feature to somehow reduce the model size to just it's points and there coordinates. autocad seems to be quite limited in handling bigger files and it's painful for the client.
I know i could reduce by smoothen mesh, but that's not what i want. I want to keep the good information and have a nice and dense mesh. But i don't need all the faces to be exported as well. They are dumb anyway as far as i realized.

Thanks for your reply.
Was nice meeting you guys at Intergeo in Hamburg.

 :)

Keep up the good work

Alex

84
General / 3D model (mesh) export // reduce to points only?
« on: November 03, 2016, 02:56:11 PM »
Dear members,

i'd like to export the mesh of a survey to the wide field of autodesk (mainly AutoCAD) tools for my client.
I decided to use DXF 3DFaces but the scale of the model was lost and there was no reference left.

I have two questions now:
1) Is there an export format which keeps these information?

2) Is it possible to reduce the mesh information on it's referenced points only (and having AutoCAD doing the meshing)?


Thanks a lot.

Alex

85
General / Re: How to project curved wall into plane
« on: October 04, 2016, 05:28:01 PM »
Hello Chris,

you will loose all the detail level if you create a texture from the pointcloud instead of projecting the original photos onto the structure.

Is there no simple way to "define" a projection (NOT planar, but cylinder or sphere) and let Photoscan project the photos that are already in use within the software?

Thanks for your help

Alex

86
General / Re: Unfolding the tower 3D model
« on: October 04, 2016, 05:14:56 PM »
Hello Chris,

as far as i can see the unfolding in CloudCompare is only for the pointcloud itself - not for the orthophoto as requested by packy_GIS.

Am i wrong, or is there any new solution by now, since i also have to "unwrap" a cylindrical orthophoto from a bend ceiling.

Greetings.
Alex

87
Feature Requests / Re: Add Scale bar option during ortophoto export
« on: October 04, 2016, 04:07:12 PM »
I would also like to have this feature.
After all the referencing work for our clients a scale bar in the orthophoto output would be great.

Thanks

Alex

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