International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Volume XXXIX-B4, 2012
XXII ISPRS Congress, 25 August - 01 September 2012, Melbourne, Australia
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facilitate scale analysis, point cloud is appropriately vacuated.
So the following data combinations are acquired: (0.056m,
0.65 point / m 2 ) , (0.056m, 1.306 point / m ) , (0.11m,
1.306 point tm ) and (0.25m, 1.306 point lm ) .
5.2 The Registration Result of Single Image and LiDAR
Points Data
The registration of one-chip frame aerial image and LiDAR
point clouds data. Registration model is shown as (2). 16
checkpoints, absolute accuracy of registration result is shown in
table 1, and the unit is m.
Single
Image Resolution (m)
0.056m
0.11m
0.25m
0.056m
Density
Point cloud density (points/ nr)
1.306
1.306
1.306
0.65
Accuracy(m)
0.2125
0.3978
0.4984
0.2237
Table 1: registration result of single image and LiDAR points
data (experiment 1)
5.3 The registration result of multi-images and LiDAR
points data
The registration model of multi- mages and LiDAR points data
still is as shown in (2). 10 checkpoints are used to check the
registration result of airborne LiDAR point clouds data with
point feature and remote sensing image, as well as the
registration result of airborne LiDAR point clouds data with
linear feature instead of point feature and remote sensing image.
The registration results are shown as table 2 and table 3.
Multi-image
scale
analysis
Image Resolution (m)
0.056m
0.11m
0.25m
0.056m
Density
Point cloud density (points/ nr)
1.306
1.306
1.306
0.65
Accuracy(m)
0.139581
0.242089
0.268104
0.177526
Table 2 Registration result of multi- images based on point
feature and LiDAR point clouds data
Multiple
DMC
Image Resolution(m)
0.056
0.11
0.25
0.056
Density
Point cloud density (point/ nr)
1.306
1.306
1.306
0.65
Accuracy(
m)
0.055636
0.091570
0.143567
0.132470
Table 3 Rgistration result of multi-image based on linear
feature instead of point feature
It can be seen from the tables above that in the registration
based on linear feature instead of point feature when flying
height is no more than 2500m and point clouds density is more
than 1 point/m“, coordinate deviation accuracy is in a pixel with
accuracy of 0.15m, the result is shown in figure7 a-c. By
comparing table 2 and 3, the accuracy using linear primitives is
much better than using point registration primitive. And, the
registration accuracy of multi-images is better than single
images.
(c)
Fig.7 Registration result of multi- images and LiDAR points
5.4 Scale analysis of image and LiDAR point clouds data
registration
With the registration results of LiDAR points data with different
density, and multi-images with different flying heights, the
profile of scale factor S, registration error and scale analysis
parameters are shown in figure 8:
0. 056-1. 306 j
0. 11-1.306 I
0.25-1.306 ;
0. 56-0. 65 1
Figure 8: registration results’ position deviation of check points
What can be seen from table 4 and table 2 is that the higher
resolution of DMC aerial image, the higher absolute accuracy of
registration.When points’ density is fixed, the higher image’s
resolution, the larger registration scale and the bigger
registration deviation. When image resolution is fixed, the
smaller density of points, the larger value of registration scale
factor and the bigger deviation of registration point position.
From figure 8, it can be seen that under original point clouds
density, the deviation of checkpoint is rather steady in the range
of [0,1.5]. Resolution of aerial image satisfies centimeter
accuracy level. Assume image resolution is 0.05m, points
density then should be 1.7 point / m , so it can get the
registration accuracy in a pixel.
5.5 The analysis of the patameter ^
In this paper, /L is introduced to make the line features in the
LiDAR points data as registration primitives corresponding to
the tie point selected in the image data. In order to verify the
impaction of the initial X value, we compare three groups of
the X values: “true values”, “the results with good original
values” and “the results with 0 original values ” .
true values
Result with good
original value
Result with “0”
original value
0.21
0.209663
0.209653
0.84
0.83865
0.83895
1.18
1.185947
1.185944
1.68
1.678126
1.678176
2.435
2.425356
2.425356
3.06
3.062787
3.062791
6.96
6.96088
6.96087
Table 4: comparation of results with differemt orginal values