NAME
SoGeoOrigin -
The SoGeoOrigin class is used to specify an absolute geographic
location against which geometry is referenced.
FILE FORMAT/DEFAULTS:
SYNOPSIS
#include <Inventor/nodes/SoGeoOrigin.h>
Inherits SoNode.
Public Member Functions
SoGeoOrigin (void)
virtual void doAction (SoAction *action)
virtual void callback (SoCallbackAction *action)
virtual void GLRender (SoGLRenderAction *action)
virtual void getBoundingBox (SoGetBoundingBoxAction *action)
virtual void getMatrix (SoGetMatrixAction *action)
virtual void pick (SoPickAction *action)
virtual void getPrimitiveCount (SoGetPrimitiveCountAction *action)
Static Public Member Functions
static void initClass (void)
Public Attributes
SoSFVec3d geoCoords
SoMFString geoSystem
Protected Member Functions
virtual ~SoGeoOrigin ()
Detailed Description
The SoGeoOrigin class is used to specify an absolute geographic
location against which geometry is referenced.
FILE FORMAT/DEFAULTS:
GeoOrigin {
geoSystem [’GD’, ’WE’]
geoCoords 0 0 0
}
A common problem when dealing with geographic data is the reduced
floating point precision you often get. UTM coordinates are often in
the 10^5 a 10^6 magnitude, and this leaves very little precision for
details at that position.
The SoGeo nodes are therefore useful when you want to keep your data in
its original system, but still get good floating point precision when
rendering.
Coin needs a local Cartesian coordinate system when rendering. When a
SoGeoOrigin node is used, Coin will create a coordinate system at the
SoGeoOrigin position, and all geometry (and the camera) in the scene
graph will be projected into that coordinate system.
The coordinate system will always have the Z axis point up from the
ground. The Y axis will point towards the north pole, and the X-axis is
found using the right hand rule.
A scene graph should only contain one GeoOrigin node, and all geometry
in the scene graph will, as stated earlier, be rendered relative to
this position. This means that the precision will be best if the
GeoOrigin position is as close to actual camera position as possible.
If you move around on a large area, it might therefore be a good idea
too actually move the GeoOrigin postition instead of the camera.
To place geometry in the scene graph, you can either use an
SoGeoSeparator node or an SoGeoCoordinate node. When using a
GeoSeparator node, all geometry inside that separator will be rendered
relative to its geo-system position and orientation, and you then use
regular shapes and regular SoCoordinate3 nodes to specify data (the
points in an SoCoordinate3 must be adjusted to be relative to the
GeoSeparator position).
The SoGeoCoordinate node on the other hand can contain double precision
geo-coordinates, and that node will internally recalculate the double
precison array to a single precision array which is relative to the
SoGeoOrgin node.
One note regarding UTM projections: Since it’s quite common to assume a
flat earth when working with UTM data, it’s possible to supply a ’FLAT’
keyword for UTM coordinate systems:
GeoOrigin {
geoSystem [ ’UTM’, ’Z17’, ’FLAT’ ]
geoCoords 846889 4313850 0
}
Example scene graph:
GeoOrigin { geoSystem ’GD’ geoCoords 40.77 -73.97 0 }
GeoSeparator {
# New York, NY
geoSystem ’GD’
geoCoords 40.67 -73.94 0
BaseColor { rgb 0 1 0 }
Cube { width 25000 height 25000 depth 25000 }
Translation { translation 0 0 30000 }
Text2 { string ’New York’ }
}
GeoSeparator {
# Los Angeles, CA
geoSystem ’GD’
geoCoords 34.11 -118.4 0
BaseColor { rgb 1 0 0 }
Cube { width 25000 height 25000 depth 25000 }
Translation { translation 0 0 30000 }
Text2 { string ’Los Angeles’ }
}
GeoSeparator {
# Washington, DC
geoSystem [ ’UTM’, ’Z17’ ]
geoCoords 846889 4313850 0
BaseColor { rgb 0 1 1 }
Cube { width 25000 height 25000 depth 25000 }
Translation { translation 0 0 30000 }
Text2 { string ’Washington’ }
}
# add a small geogrid
GeoCoordinate {
geoSystem ’GD’
point [
32 -120 0,
32 -110 0,
32 -100 0,
32 -90 0,
32 -80 0,
32 -70 0,
34 -120 0,
34 -110 0,
34 -100 0,
34 -90 0,
34 -80 0,
34 -70 0,
36 -120 0,
36 -110 0,
36 -100 0,
36 -90 0,
36 -80 0,
36 -70 0,
38 -120 0,
38 -110 0,
38 -100 0,
38 -90 0,
38 -80 0,
38 -70 0,
40 -120 0,
40 -110 0,
40 -100 0,
40 -90 0,
40 -80 0,
40 -70 0
42 -120 0,
42 -110 0,
42 -100 0,
42 -90 0,
42 -80 0,
42 -70 0
]
}
DrawStyle { style LINES }
BaseColor {}
ShapeHints { vertexOrdering COUNTERCLOCKWISE }
QuadMesh { verticesPerRow 6 verticesPerColumn 6 }
Since:
Coin 2.5
Constructor & Destructor Documentation
SoGeoOrigin::SoGeoOrigin (void) Constructor.
SoGeoOrigin::~SoGeoOrigin () [protected, virtual] Destructor.
Member Function Documentation
void SoGeoOrigin::initClass (void) [static] Sets up initialization for data
common to all instances of this class, like submitting necessary
information to the Coin type system.
Reimplemented from SoNode.
void SoGeoOrigin::doAction (SoAction * action) [virtual] This function
performs the typical operation of a node for any action.
Reimplemented from SoNode.
void SoGeoOrigin::callback (SoCallbackAction * action) [virtual] Action
method for SoCallbackAction.
Simply updates the state according to how the node behaves for the
render action, so the application programmer can use the
SoCallbackAction for extracting information about the scene graph.
Reimplemented from SoNode.
void SoGeoOrigin::GLRender (SoGLRenderAction * action) [virtual] Action
method for the SoGLRenderAction.
This is called during rendering traversals. Nodes influencing the
rendering state in any way or who wants to throw geometry primitives at
OpenGL overrides this method.
Reimplemented from SoNode.
void SoGeoOrigin::getBoundingBox (SoGetBoundingBoxAction * action)
[virtual] Action method for the SoGetBoundingBoxAction.
Calculates bounding box and center coordinates for node and modifies
the values of the action to encompass the bounding box for this node
and to shift the center point for the scene more towards the one for
this node.
Nodes influencing how geometry nodes calculates their bounding box also
overrides this method to change the relevant state variables.
Reimplemented from SoNode.
void SoGeoOrigin::getMatrix (SoGetMatrixAction * action) [virtual] Action
method for SoGetMatrixAction.
Updates action by accumulating with the transformation matrix of this
node (if any).
Reimplemented from SoNode.
void SoGeoOrigin::pick (SoPickAction * action) [virtual] Action method for
SoPickAction.
Does common processing for SoPickAction action instances.
Reimplemented from SoNode.
void SoGeoOrigin::getPrimitiveCount (SoGetPrimitiveCountAction * action)
[virtual] Action method for the SoGetPrimitiveCountAction.
Calculates the number of triangle, line segment and point primitives
for the node and adds these to the counters of the action.
Nodes influencing how geometry nodes calculates their primitive count
also overrides this method to change the relevant state variables.
Reimplemented from SoNode.
Member Data Documentation
SoSFVec3d SoGeoOrigin::geoCoords Used for specifying the geographic
coordinates. For the GD system this should be <latitude> <longitude>
<elevation>. For UTM it is <easting> <northing> <elevation>, and for GC
it is simply <x> <y> <z>.
SoMFString SoGeoOrigin::geoSystem Used to specify a spatial reference
frame. Coin currently supports three different systems. Support for
more systems might be added in the future.
·
·
·
The ’GD’ and ’UTM’ systems can, for future support, have an ellipsoid
specification. The default is ’WE’ which is the WGS84 ellipsoid, the
only ellipsoid currently supported in Coin.
Author
Generated automatically by Doxygen for Coin from the source code.