Hi GRASSlist,
has anybody implemented/used Stereo-0.2 together with Grass?
I myself used it a lot during the last month in order to generate
cheap DEM Data for our telescope project. (http://dts.astronomy.net)
It seemed to be logical to offer it in a polished form to other GIS
(eh GRASS users) users as well. (currently it's glued to GRASS
with some ugly shellscripts and stereo needs a bit of rewrite as well)
Currently I use it as follows:
(You may calibrate using any 4+Polygon like TP's etc. which are
visible in at least two photos)
Put a multi-colored cube wireframe of known dimensions out in the
location (level it using some standard method), write down it's
relative coordinates. (used for Image calibration later on)
Take as many photographs as seem appropriate (always with
cube included). (at least 2 photos are necessary)
Calibrate images using known info (relative cube coordinates) within
stereo (display). Triangulate points of interest. ...
with additional import and manipulation within grass to follow.
If there is enough interest in merging stereo to grass, i will
write/rewrite a grassmodule / stereo.
(perhaps as an extension to OrthoRectificationSupport)
Pros:
pretty random Camera placement (cam location hasn't to be known!)
pretty high quality results (depending on calibration points)
one person usage of complete system (it's easy to deploy
a "calibration" object and taking photos of it.)
reusable datasets (Photos taken may be reviewed afterwards
for other - former unknown - topics without having to
survey the points of interest again.)
cheap (A simple camera/scanner system)
fast (doing some snapshots at more or less random positions
really doesn't cost to much time)
interoperates well with GPS/Remote Sensing)
Cons:
currently buggy software / no plug and play module as of now
you can only measure what you can identify (as good/bad as v.digit)
Plans:
Reimplementing stereo within tk and a c library.
Providing hooks for grass and image registration.
Let me know if there is already some tool/module out there (GPL or sim.)
(i.ortho.* doesn't count as it requires camera location as well
as other accurate data not always at hand (according to GRASS Handbook))
best regards,
Christoph Hoegl
(Stereo is a (pretty old) GPL package for stereo photogrammetry))
---------------LSM Entry-----------------------------------
Begin3
Title: Stereo
Version: 0.2
Entered-date: 06OCT97
Description: Stereo-photometrology package. A tool
for loading up high res grey tiff/targa
files of stereo photographs and
taking accurate 3D measurents from them.
Keywords: XLib, X Window System, X11, stereo,
photometrology, CAD, measurement,
Cooledit
Author: psheer@icon.co.za (Paul Sheer)
Maintained-by: Nobody
Primary-site: sunsite.unc.edu /pub/Linux/apps/math
3193kB stereo-0.2.tar.gz
1kB stereo.lsm
Platforms: Linux, and any Unix clone running X11
Copying-policy: GPL
End
------------------LSM Entry-------------------------------