Forum

Author Topic: Difference between Orthophoto and true orthophoto  (Read 7818 times)

Ingsayyad

  • Jr. Member
  • **
  • Posts: 89
    • View Profile
Difference between Orthophoto and true orthophoto
« on: May 15, 2015, 12:23:56 PM »
I want to see fine details on my orthophoto/trueorthophoto. I'm little bit confused about  the description of  Orthophoto and true orthophoto.

What we are getting from photoscan is dense pointcloud  projected on to user defined plane (orthophoto) but how can I get true orthophoto.

http://en.wikipedia.org/wiki/Orthophoto



see :http://en.wikipedia.org/wiki/Orthophoto
Below is decription of the orthophoto:

This photo is properly projected on elevation model, yet on a single building scale, a small tilt is noticeable due. This is an Orthophoto, but not a True Orthophoto (not all vertical features are reprojected).



see :http://en.wikipedia.org/wiki/Orthophoto
Below is decription of the truephoto:
This photo is assembled from several overlapping photos from UAV, completely removing any residual tilt of the buildings. This is a True Orthophoto.

GeoGecco

  • Newbie
  • *
  • Posts: 31
    • View Profile
Re: Difference between Orthophoto and true orthophoto
« Reply #1 on: May 15, 2015, 01:37:24 PM »
you can use markers to define a specific plane when exporting othophotos.
When I need to export orthophotos of facades I usually export the pointcloud to autoCAD, define 3 points which are in the facade coordinate system and then import those 3 points to photoscan.
When exporting orthophoto I choose planar and projection plane choose "markers" and do:

points: 1001, 1002, 1003

1001
    |
    |
1002 ----------- 1003


  o  Horizontal: 1002 -> 1003
  x  Vertical : 1002 -> 1001

and check the box right next to vertical axis


thats how it works for me
I don't get any tilting effects
« Last Edit: May 15, 2015, 01:42:48 PM by GeoGecco »