

Photographic Intersection
 a brief overview
The low cost
method for accurately measuring 3D points. 





Photographic Intersection
 how I
developed my ideas
A brief
history of the events and ideas that developed into my views
on Photographic Intersection. 





Photographic Intersection
 the technicalities
The
technical details that support Photographic Intersection. 





The Use of Spherical (360°) Panoramas for
Photogrammetry
Spherical
Panorama projections
are suitable for the extraction of measurements to compute
the 3D coordinates for points from two or more panoramas.
The mathematics involved is much more straight forward than
that required for using photographs for Stereo
Photogrammetry and Photographic Intersection.
Horizontal and Vertical angles are easily measured in an
Equirectangular projection to provide the same data as if a
theodolite was used at the same location. 





Accuracy
for Intersection
The accuracy
for a point measured using an Intersection method is
determined by three interrelated factors:
the separation of the Stations (Base Line),
the Angle of Intersection and
the Precision of the Angular Measurements. 





Practical Evaluation of Accuracy
for Measurements from Panoramas
Practical exercises to evaluate the accuracy of measurements
from 360° Panoramas. 





Spherical Panoramas for Photogrammetry
3D
measurement techniques are readily available, but low cost
solutions are needed for applications where only a small
quantity of data is required. Measurements can be made
from Spherical Panoramas using available techniques, but
these are time consuming, error prone and laborious, so this
is an appeal to those with skills in software development in
the fields of digital imaging and the mathematics to compute
intersecting rays in space to provide a viable and cost
effective solution. 





Using 360° iSTAR Panoramas to add
Detail to an HDS Point Cloud
Real world
colour can be added to the points in a Point Cloud from cocentric 360°
(spherical) panoramas and some users have found that it is also
beneficial to take additional 360° panoramas. This task takes
this one stage further and uses 360° panoramas to add detail to a survey
initially made with an HDS Scanner. 





Image Assisted Surveying
In October 2010,
Leica Geosystems
introduced Image Assisted Surveying on their Total Stations with the
introduction of the Leica Viva Imaging
Total Stations. This product
greatly enhances the functionality, ease of use and
productivity of the onboard applications and provides useful
features for Photogrammetric and Photographic Intersection surveying
and mapping techniques.






360° Panoramic
Optic for Photographic
Intersection
A Conical
Mirror or Prism to provide a full 360° panorama for
surveying and mapping. 





Panoramic
Photography As A Survey Tool
A paper
describing the development of an optical device for use in
detail surveying, which enables panoramic photographs to be
taken using conventional cameras and lens systems, and
suggests how such a device can be used as a tool in some
survey disciplines.
Author:
Hugh Anderson, 1st August 1978






Determining the
Nodal Point of a Lens
For a lens
to be used effectively for
Photographic Intersection the
location of the Front Nodal Point
must be
accurately determined. 





The Nodal Point
The case for the Nodal Point and usage of the term.. 





Photographic Intersection by Light Line for measuring
Tunnels
Images of
the FITS and HITS units being used to measure tunnel
profiles. A Light Line is projected onto the tunnel
surface defining a plane through the tunnel at the
particular chainage require. This is photographed and
digitised to produce an accurate profile of the tunnel.
A 1000 metres of tunnel could be measure every 10 metres in
a single nights possession using this technique. 





Patent No. 1493188
Optic for
instantaneously photographing an horizon of 360°. 





Optic for
instantaneously photographing an horizon of 360°
Patent specification
GB1493188, 22nd April 1975.






Method and apparatus for photographic
tunnel sectioning
European patent
application.
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