Nanjing Institute of Surveying Mapping & Geotechnical Investigation, Co. Ltd. 
8 WangFu Avenue Xinjiekou Square Nanjing 210005, P. R. China - cspringhwq@yahoo.com.cn. 
KEY WORDS: LiDAR, Surveying, Analysis, DEM/DTM, Accuracy, Test 
ABSTRACT: 
There are over 10 sets of LiDAR system into China until end of 2007, but they did not in full of working. One reason is big capacity 
of the market need a long period time. Another is author of this article concerned that is accuracy of LiDAR data when it does 
surveying projects. In this article, the author make the analyze accuracy of LiDAR data base study site in Nanjing, China. All of them 
are from point of view productions of surveying and mapping. Last, the author make conclusion: LiDAR data acquiring is important 
and accuracy of LiDAR data is good, especially accuracy of DEM/DSM productions is very well. 
1. INTRODUCTION 
1.1 LiDAR technology developing is faster than before in 
China 
Nowadays, LiDAR (Light Detecting And Ranging) is more and 
more frequent used in all kinds of fields, such as forest 
measurement, transportation and power transmission fields. A 
lot of enterprises want introduce LiDAR systems and software 
into China from abroad, which are close related surveying and 
mapping field. Until end of 2007 year, there are over 10 sets of 
LiDAR systems coming into China and extending surveying 
and mapping market. They are nearly including all kinds of 
type of LiDAR systems by commercial vendors: Optech, Leica, 
LitterMapper, Riegl, and TopoSys. The first commercial 
LiDAR system came into China in 2004. It is a quite big 
problem how to put them in full working, because big capacity 
of the market need a long period time. 
1.2 The feature of LiDAR data 
Airborne LiDAR data is including point clouds and images. 
Point clouds have horizontal and vertical positional information 
and intensity. Images are acquire if laser scanner with a digital 
camera. We can make DEM/DSM (Digital elevation Model or 
Digital Surface Model), DOM (Digital Orthoimages Mapping), 
DLG (Digital Line Mapping) and three-Dimensional Models 
(3DM) with LiDAR system. In survey and mapping field, 
LiDAR data have several benefits: first, it can get precise 
elevation of ground, trees and buildings, which can only be 
obtained by conventional aerial photography method before. 
Moreover, LiDAR method has more accurate than it. Second, 
points and images of LiDAR systems can be used to build 
three- dimensional models without current topographical map. 
This broke up current circle procedure of making 
three-dimensional models. 
1.3 Accuracy of LiDAR data 
In China, because the LiDAR system and main interrelated 
technique came from foreign country recent year, users do not 
really grip how much the deviations to practical value will be 
occurred if use LiDAR system doing projects, as well as how to 
control them. Morsdorf et al. [2004] and Lukas Wotruba[2005] 
put 4 cardboard covered tables at comer of study site to 
compute the planimetrie offsets, height offset and height 
variations of the raw laser data. They make a perfect test on 
characters of raw laser data, but few people give a good 
comparison of four-D (DEM, DOM, DLG, and DM) production 
from two kinds of data source and methods: photogrammetry 
and LiDAR. This article will describe accuracy of LiDAR data 
from point of view production of it. 
2. STUDY AREA 
LiDAR data were collected over the study area in March, 2006 
with an ALTM3100 Optech system mounted on a fixed wings 
airplane platform by Nanjing Institute of Surveying Mapping & 
Geotechnical Investigation, Co. Ltd. There are one small hill 
and several roads with many buildings standing on two of sides. 
The site is near downtown of Nanjing, Jiangsu province of 
China. Following picture (figure 1) will show the details of the 
study area. 
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