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The 3rd ISPRS Workshop on Dynamic and Multi-Dimensional GIS & the 10th Annual Conference of CPGIS on Geoinformatics
Chen, Jun

ISPRS, Vol.34, Part 2W2, “Dynamic and Multi-Dimensional GIS”, Bangkok, May 23-25, 2001
File Edit Marking Referencing Project Display Window . Help
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immediately obtained: 74cm. This could be a very convenient
and attractive function for many users. The firemen for example,
would appreciate this approach for obtaining the sizes of some
doors and windows immediately in case of fire. This is much
Fig. 3. Direct measurement of a window width on the digital photograph (source: Deng, [1999, p.61]).
more user-friendly and reliable compared with the practice of
identifying the right lines and figures in the complex engineering
drawings, especially for the people who are not familiar with the
engineering drawings. The accuracy of the distance, when
dealing with the non-metric digital camera image and no
pre-calibrations for the camera, could be up to 1/1,700 in object
space according to the test made by the author (Deng, 2001) by
using PM Pro. Better accuracy was reportedly achieved by
pre-calibration of the cameras with the Camera Calibrator
provided by PM Pro (Hanke, 1998). Even higher accuracy could
be expected when metric cameras were used. It remained as a
problem however when scanned hard copy images were used
and the modeling of the scanning errors, including the
dominating geometric errors and sometimes the less dominating
radiometric errors, were not properly handled (Shortis and Beyer,
1996), it brought about obvious influences on the accuracy.
3. 3D Model Construction and Direct 3D Measurement:
Different forms of output are available from PM Pro, including
table text formats of the analytical results of 3D coordinates and
camera parameters, ortho photos of selected planes and
adjusted 3D models with or without photo texture for 3D viewing,
CAD or animation. The frame of the 3D model is constructed by
the adjusted 3D points marked for processing or measurement
in advance. The model can be optionally formed by points, lines,
surfaces and photo texture surface covered model with or
without point and line marks. The formats of the PM Pro output
are compatible to most of the related current data formats,
including text formats, image formats and CAD formats. Once
the 3D model is constructed by PM Pro, it can be used for both
3D viewing and direct 3D measurement. For 3D viewing, a 3D
model produced by PM Pro can be viewed from different angles
by rotating the model on computer screen with the mouse, the
model can also be magnified or minified on the screen. As a
good example of the application of the 3D model created by PM
Pro, an impressive virtual reality modeling project can be found
in a EOS project on the web (EOS, 2001). The viewer “walks” in
this project through a downtown street formed by a VRML model
created with PM Pro. 74 photographs and over 1000 3D points
were used in PM Pro for the modeling. The animation effect and
the photo texture covering over the model makes a good real life
result. For the direct 3D measurement, the 3D point coordinates,
distances and areas can be measured directly on or between the
point marks on the 3D mode under the measure mode.
4. Engineering Drawing Production: The engineering
drawings of an object can be obtained by loading the 3D result
of PM Pro into CAD after PM Pro has finished processing the