The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences. Vol. XXXVII. Part Bl. Beijing 2008 
A monochrome shaded point map is a map that the ground 
points extracted from the filtering process are overlaid on a 
shaded map created from DSM data. Figure 2 shows a 
monochrome shaded point map. The ground data to be used are 
shown in small red points. The places in dark red area in the 
map are the places where the measurement data coincide and 
thus have high point density. The shaded map is presented in 
monochrome depends on the amount of shadow. And the 
ground points are presented in the plainly different color from 
the monochrome shaded map. The following are the 
advantages of using a monochrome shaded map as the 
background: 
2.1.1 Easy Viewing of Ground Objects: the shaded map 
does not interfere with the display of the point clouds that are 
targeted for examination. It allows interpretation of topography 
and features. 
2.1.2 Data Created from Measurement Data: As it is 
created from measured data, it is possible to determine whether 
measurements have actually been taken or not. 
2.1.3 No Distortion and Halation: there is no distortion or 
halation of the buildings that is quite different from the aerial 
photograph. Because the monochrome shaded point map is 
generated only from the Lidar point clouds. 
2.1.4 No Special Equipment for 3D-Recognition: It allows 
3D-recognition without special equipment or spectacles. 
Figure 2 Monochrome Shaded Point Map 
2.2 Disadvantages of a monochrome shaded point map 
While the legibility of point clouds after filtering is high, one 
disadvantage of a monochrome shaded point map is that it 
cannot be used alone. Figure 3 shows a monochrome shaded 
point map in a forested area. It is impossible to interpret 
whether point clouds displayed on the map represent ground 
point data or feature data derived from the measurement of the 
tops of trees. Comparison with another QC/QA map is required 
to verify whether the feature data of the forest remain on the 
map or not. 3 
3. DESCRIPTION OF QUALITY CONTROL METHOD 
3.1 Outline and Features of Quality Control Method 
As mentioned above, in some cases, the interpretation of 
monochrome shaded point maps can be problematic, and in 
such cases the quality control of the maps may not be 
satisfactory. To solve this problem, we developed a new 
quality control method using both monochrome shaded point 
maps and color-shaded maps. Figure 4 shows the workflow of 
the new QC/QA method. 
Figure 3. Monochrome Shaded Point Map of a Forested 
Area 
Figure 4. Workflow of the Quality Control Method 
3.2 Examination of the Color-Shaded Map 
It is known that a color-shaded map allows the presentation of 
micro topology. The filtering results that are examined using 
this QC/QA map are shown in Figure 5. The reasons for 
choosing the color-shaded map are as follows: 
• A color-shaded map is suitable for detailed examination of 
forests, which cannot be examined with a monochrome 
shaded point map. 
• It can be created automatically and is suitable for 
processing a large amount of data. 
• Feature data remained after filtering have an elevation 
different from the surrounding topography, and this 
difference creates a shadow on the color-shaded map. This 
shadow serves as a reference and provides a clear basis for 
decision-making in the examination of the filtering (shown 
in Figure 6) . 
• It enables examination of detailed and fine feature data.