grammetry, Remote Sensing and Spatial Information Sciences
. Vol XXXV, Part B4. Istanbul 2004
International Archives of the Photo
Texture LOD layer Texture ID Texture Size Texture Data 05
0 1096 64X64 JPEG2000Byte []
Surface | 1 1096 32X32 JPEG2000Byte []
texture | 2 1096 16X16 JPEG2000Byte []
3 1096 8X8 JPEG2000Byte []
0 1262 128X64 JPEG2000Byte []
Surface 1 1262 64X32 JPEG2000Byte []
texture? 2 1262 32X16 JPEG2000Byte []
3 1262 16X8 JPEG2000Byte []
Tablel. The structure of multi
4.2 Visibility-based city scene visualization
When the user begins to roam the city scene, a set of
parameters such as the height of viewpoint, angle of view
(AOV), pitch and yaw are computed.
The data cache of nine multi- resolution city blocks is obtained
from server side. In the area of data cache, there is the original
viewpoint (point A) and the end of viewpoint (point B) (see
figure 5). While the viewpoint is moving from point A to point
B, only several data blocks need obtained from city model data
at server side, and it has enough time to transfer the data block.
At same time dynamic city scene 1s created according to the
Zz
/
FK.
N
N
x
Point A
Figure 5. LOD Blocks for Flying Operation
parameters of viewpoint.
5. NETWORK MESSAGES DESIGN
il to implement the requirements of
ironments. So, the
te each
eration
The message is proved useft
multi-user's interaction in the virtual city env
message is designed to achieve multi-users communica
other and to assure the consistency of multi-user's op
and virtual scene.
The message format is defined as follow:
<FromlD * *TolD * *msgType * *Range* *RequestReply *
msgContent>
From the ID of user who sends message to others
To the ID of user who receives the message from
message server
message type
MsgType
request reply
RequestReply
1
-resolution LOD texture
Range the range of message
MsgContent the content of message
6. EXPERIMENTS
With these methods a Web-based distributed virtual city
system together with the aspects of visualization interface is
implemented to 3D city visualize. Especially, the user can see
his avatar and other user’s avatars in the city environments.
in this system, the system application server is
Moreover,
lication server is
deployed Unix platform and the other app
deployed at Windows platform.
world, the user is able to change the
ing to his/her viewing habits, it
which
Similar to real
visualization process accord
provide a interactive process during flying through,
allows user to input information during procedure of
visualization to construct a free envision space to fly in it.
Several experimental results are shown as following in figure.6.
figure 7, figure 8.
Wie a
RE BEL WE SEW TRE
b 3 T A :
uted virtual city scene
Figure.6 the user avatar in the distrib
136
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roam
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Alexa
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Armin
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Photos