WORKFLOW AND QUALITY CONTROL TO GENERATE DEM AND DSM BY AERIAL 
PHOTOGRAMMETRY 
JIAQiuying CAO Haitang JIANG Decai ZHU Rong 
Surveying and Mapping Engineering Branch of Aerophotogrammetry and Remote Sensing Bureau of China Coal (ARSC) 
710054 - jqy691107@ 163 .com 
Xi’an, 
WG IV/l-Spatial Data Infrastructure 
KEY WORDS: Aerial Photogrammetry, DEM/DTM, Triangulation, Model Précision, CAD IKONOS 
ABSTRACT: 
DEM and DSM both are very important fundamental geographical information data. Along with the 3G technology unceasing 
development, DEM and DSM have been applied widely in the telecommunication industry. Since cooperating with Siradel France in 
2004, ARSC has produced DEM and DSM data for Hong Kong, London, New York, Romanian entire boundary, and many French 
cities including Paris. Moreover, we first use IKONOS stereo pair imagery to produce DEM and DSM data for Morocco cities such 
as Rabat and Casablanca successfully. ARSC has provided high grade DEM and DSM data, already obtained France side's complete 
approval, also made the aerial photogrammetry method to generate DEM and DSM data applied in the data production widely. In this 
article, the authors mainly introduce the workflow to generate DEM and DSM data by the aerial photogrammetry method, the 
frequently asked questions and quality control method. This will lay a good foundation for us to provide the client with satisfied 
digital products. 
1. INTRODUCTION 
DEM (Digital Elevation Model) is the digital presentation of 
regional terrain. Its mostly reflects the nature landform 
characteristics in a local area. And DSM (Digital Surface Model) 
is the digital presentation of the earth surface features. They 
biggest difference lies in that DEM only express the 
hypsography, but DSM express not only the hypsography, but 
also includes each building surface and the vegetation coverage 
situation. It reflects the surface character of all object located in 
the ground. 
Along with the rapid development of computer science and the 
aerial photogrammetry technology, the Chinese telecommuni 
cation industry also develops unceasingly following it, 3G 
mobile will enter Chinese market. 3G technology also will be 
applied widely. The aerial photogrammetry has become one of 
the most effective methods to provide high-resolution funda 
mental data for 3G technology. SIRADEL is a world leading 
provider of geographical databases, propagation models 
and radio expertise for planning and optimizing any radio 
networks worldwide, has lots of international cooperation 
partners. ARSC is one of them in Asia. In past several years, 
ARSC has provided about ten thousand square kilometers DEM 
and DSM basic data. In this article, the authors discuss the 
operation and quality control method combining with the 
practical problem appearing frequently in the production. 
2. ESSENTIAL HARDWARE AND SOFTWARE 
Hardware: SSK, ImageStation Z from Intergraph Corporation 
JX4 from Beijing Geo-Vision Tech.Co.,Ltd. 
Software: Microstation J from Bentley Systems, Incorporated 
ISDM, ISSD, ISDC, ISFC from Intergraph 
Corporation 
CAD2000 
ARSCCHECK from Siradel France 
3. TECHNICAL REQUIREMENTS 
3.1. Data Capture Requirement to DEM 
DEM data capture mainly includes road, hydrology, railroad and 
terrain feature lines, breaklines etc. various natural relief feature. 
The required accuracy of various elements to compose of DEM 
should be less than 1 meter. In order to avoid from affecting the 
precision caused by DEM’s sudden change in the short distance, 
all breaklines must be cut down in intersection area. The 
elevation value in tie-in area of linear object should be only one. 
3.2. Data Capture Requirement to DSM 
DSM data capture mainly includes various building, industry 
and mining facility and vegetation etc.. The required accuracy 
of various elements to compose of DSM should also be less 
than 1 meter, and these elements must build a topology 
relationship, one corresponding elevation value should be 
labeled within each topological surface. If the height difference 
is more than 5 meters within the same clutter object, it should 
be cut into segmentation to form several topology relations. 
Similarly, if there is a dooryard within the building, or there is 
an open area within a forest, they also must be closed by using 
the independent polygon. 
4. OPERATION METHOD 
For DEM and DSM basic data capture, Siradel France has 
provided a set of detailed technical requirement. We have 
prepared the relevant operation plan after studying their 
requirements. Our workflow is as follows: 
According to Siradel’s requirements to data, the captured data 
can be divided into three main parts: (See Figure 1. Three 
Categories of Digital Data) 
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