119 
DIGITAL AUTOMATIC ORTHOPHOTO PRODUCTION 
WITH LASER LOCATOR AND AERIAL PHOTOGRAPHY DATA 
Evgueny Medvedev 
Opten Limited, Moscow, Russian Federation 
Commission V, Working Group 4 
KEY WORD: Laser scanning, digital aerial camera, orthophoto rectification, DTM, IMU 
ABSTRACT 
Application of traditional aerial survey technologies for topographic purposes has a number of principal problems. 
The most serious problem is definitely impossibility of automatic use of classical stereophotogrammetry methods in 
cases of complex terrain, urban areas, the areas with no visual texture and so on. 
It is well recognized by now that laser locator methods are very efficient for such kinds of work. The proposed 
approach is based on the following main principles: 
1) Original 3D nature of laser locator data in combination with an absolute geodetic accuracy of 10-15 cm, 
unachievable to traditional methods of aerial topography survey, allows to suggest a number of effective algorithms of 
fully automatic recognition, delineation and positioning for the objects such as Digital Terrain Model (DTM), water surface 
contours, forest arrays, single trees, buildings. 
2) Laser locator survey can be successfully combined with digital aerial photography during both on-board data 
acquisition and on-ground processing. Indeed, the application of Global positioning system (GPS) navigation complex + 
inertial measurement unit (IMU) on board required for correct laser locator data interpretation makes it possible to record 
3D coordinates of principal points and angles of optical axis orientation for each frame, which in turn provides the 
99999999999999 
Presented approach ensures automatic topographical mapping in scale 1:2000 - 1:5000 with total productivity of 
200-300 km per day. The special software for automatic mapping and some examples of realization are described. 
1. CLASSIC STEREOTOPOGRAPHIC METHOD: 
ADVANTAGES AND PROBLEMS 
Despite the permanent development of digital 
photogrammetry methods the complete automation of 
relief part of map production and orthorectification of 
aerial photos can hardly be achieved within the classic 
approach. Leaving alone the outdated and extremely 
unproductive purely ground based methods of relief 
depiction, a currently dominating based on aerial survey 
data so called stereotopographic method of production 
and upgrading topographic maps and plans, is 
reviewed, that method allows both relief reproduction 
and orthorectification in cameral conditions. An attempt 
to automate the method faces the complications 
conditionally divided in two categories: 
1) Disadvantages of method. This category is made up 
of a group of major photogrammetric problems, which 
being put together mostly limit the method application in 
topography in general. By recent times such were 
rather considered as natural limits of application but not 
problems. Reference to them as the problems is now 
due to recent alternative solutions appearance. 
Stereotopography method assumes the imperative on 
ground geodetic plan/elevation support of aerial survey 
results. Within such, a limited in volume geodetic survey 
of the area relief is performed, that is conditioned by 
high cost and low productivity of on-ground geodetic 
works. The results on this stage, being spatial 
coordinates of ground control points, are only used for 
photo triangulation extension, that results in supporting 
geodetic net spreading on all aerial photos of a project 
thus providing each with 5-6 secondary control points. 
This in turn allows absolute spatial orientation of 
photos, and their mutual orientation in stereopairs, upon 
which one may immediately begin retrieval of relief in 
absolute coordinates and orthorectification. Such is, in 
brief, a content of the classic stereotopography method 
that is obviously well known to everyone aware of 
photogrammetry in general. 
The major conclusion that can be done of the above 
brief description is - so produced relief model is only 
with small degree (particularly in a volume of on-ground 
geodetic support) provided with independent control 
measurements. The rest of necessary information 
appears within the stereotopography method itself, and 
therefore by definition contains no mechanism of 
correctness and accuracy control. 
The above described technique may be, indeed, divided 
into four general processes: