Topics

1

General / Marker and GCP Question

« on: June 11, 2017, 09:26:57 AM »

I am using PS for areal mapping with a drone (GPS in EXIF).
I am satisfied with the orthomaps (X/Y) that PS creates, even without GCPs.
But usually the altitudes(elevations (Z) are quite bad.

Normally I get the elevation of boreholes from the company which does the field work.
These elevations are good, but the easting and northing, which the company measures "by hand" is not.
So I cannot use theses values as GCPs.

Now I want to combine the "good" X-Y-values from PS with the "good" elevations of the boreholes and use the combination as GCPs.
The plan ist, to create markes at the position of the boreholes and insert the elevation manually.

Is there a way to get the easting and northing automatically (from the position of the markers in the orthomap)?
Then I only have to insert the elevations by hand, this would be comfortable. 
 

2

General / Meaning of "ground altitude"

« on: April 02, 2017, 12:53:54 PM »

The reference pane, reference settings has a field

"Ground altitude [m]"

What does this mean?
The altitude of the UAV over the starting point?
The altitude of the ground at the starting point?
The middle, lowest or highest altitude of the terrain?
Or what else?

3

General / Merging Chunks

« on: February 16, 2017, 03:35:04 PM »

I expect a bigger project in the near future, so I started to work with chunks.

For testing I took a (quite small) set of fotos and first made a "normal" modell (just one chunk), which was ok.
Then I took 3 parts of the same foto-set and made 3 chunk and modells.
The chunks "overlapped", means, I used some equal fotos from chunk 1 in chunk 2 and from chunk 2 in chunk 3.

All chunks were calculated in the same way (medium allign and medium dense cloud).
The results of the single chunks were ok.
But after merging the  3 chunks to one chunk, there are ghosts and blurry parts, see attachment.

Where is my mistake ?

4

General / Flight plan against bowl effect

« on: October 07, 2016, 02:23:50 PM »

Maybe this ist of interest for other users:

Thanks @bemis I could read this article:
http://onlinelibrary.wiley.com/doi/10.1002/esp.3609/full

As I often have problems with the bowl-effect when creating DEMs, I tried it out.

First I planed and made an "normal" UAV-flight with 68 nadir fotos.
The result (DEM) was quite poor, with a big bowl-effect.
Then I took 10 more fotos and tilt the camera for 30°.
I alligned the nadir and oblique fotos.
The resulting DEM (78 fotos) did not show the bowl effect. 

In the attachments you can see the flight plans, the dense clouds, the DEMs and profiles.
I did not use any GCPs.
It also works wit other tilt-angles of the camera.