Hi Brian,
Yes, my tiles are a lot larger than 2000 meter. The radius of the first tile is
9008.5 m, and the road segment contained in that segment is 18017 m. But should
really the range value be connected to the tile size?? I my mind it should work
in the way that if my eye point comes within the specified range the LOD tile
should appear. And by "within range" I mean that distance from the eye point to
the edge of the bounding sphere of the tile. But maybe I have completely
missunderstood the concept here??
Best regards,
Björn
Hi Bjorn,
It looks like the problem is your tiles are larger than 2000 m radius.
Try setting the range to the tile radius, or some multiple (1.5 * radius,
2.0 * radius).
Brian
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-----osg-users-boun...@lists.openscenegraph.org wrote: -----
To: "OpenSceneGraph Users" <osg-users@lists.openscenegraph.org>
From: Björn Blissing <bjorn.bliss...@vti.se>
Sent by: osg-users-boun...@lists.openscenegraph.org
Date: 08/26/2009 11:56AM
Subject: [osg-users] Paging strategies for road tiles
Hi all,
My application involves road vehicles driving down long roads. Approx 1000
km of continuous road. The problem is that I can only hold about 100 km of
road before system memory runs out. Plan B then naturally falls on some
sort of paging strategy. I rewrote the software so it generates .ive files
containing about 10-30 km road. Then the plan was to use pagedLOD to page
in the files when needed.
My test program only uses four of these tiles, but I do not seem to get it
right. My pagedLOD nodes all lie under the scene graph root. Each one only
contains a reference to the corresponding .ive file and a range set from 0
to 2000 (since I don't want the next geometry to be paged in until I am
closer than 2000 meters). The center of each pagedLOD node is set to the
center point of the geometry in the file and the radius is set to half the
length of the road in the file.
But no geometry is ever paged in.
If I set the center to (0, 0, 0) the geometry will page in the first
segment of road, but then the geometry disappears when I traveled more than
2000 meters. The other tiles never shows up.
I am obviously missing something when setting up my pagedLOD. If someone
could give me a hint I would be most thankful.
Best Regards,
Björn
If I output my scenegraph to a osg-file this is the content:
Group {
nodeMask 0xffffffff
cullingActive TRUE
num_children 4
PagedLOD {
nodeMask 0xffffffff
cullingActive TRUE
Center 8933.58 -982.774 0
Radius 9008.5
RangeMode DISTANCE_FROM_EYE_POINT
RangeList 1 {
0 2000
}
NumChildrenThatCannotBeExpired 0
FileNameList 1 {
c://tile1.ive
}
num_children 0
}
PagedLOD {
nodeMask 0xffffffff
cullingActive TRUE
Center 19930.8 8704.41 0
Radius 6001
RangeMode DISTANCE_FROM_EYE_POINT
RangeList 1 {
0 2000
}
NumChildrenThatCannotBeExpired 0
FileNameList 1 {
c://tile2.ive
}
num_children 0
}
PagedLOD {
nodeMask 0xffffffff
cullingActive TRUE
Center 34616.1 17445.3 0
Radius 11875
RangeMode DISTANCE_FROM_EYE_POINT
RangeList 1 {
0 2000
}
NumChildrenThatCannotBeExpired 0
FileNameList 1 {
c://tile3.ive
}
num_children 0
}
PagedLOD {
nodeMask 0xffffffff
cullingActive TRUE
Center 47754.4 25857.3 0
Radius 3955
RangeMode DISTANCE_FROM_EYE_POINT
RangeList 1 {
0 2000
}
NumChildrenThatCannotBeExpired 0
FileNameList 1 {
c://tile4.ive
}
num_children 0
}
}
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