Commit a8ee5059 authored by Will Schroeder's avatar Will Schroeder
Browse files

ENH:Skeleton for projecting path on terrain

parent d5fa4010
Program: Visualization Toolkit
Module: vtkProjectedTerrainPath.cxx
Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
All rights reserved.
See Copyright.txt or for details.
This software is distributed WITHOUT ANY WARRANTY; without even
PURPOSE. See the above copyright notice for more information.
#include "vtkProjectedTerrainPath.h"
#include "vtkInformation.h"
#include "vtkInformationVector.h"
#include "vtkObjectFactory.h"
#include "vtkPriorityQueue.h"
#include "vtkImageData.h"
#include "vtkPolyData.h"
#include "vtkPointData.h"
#include "vtkPoints.h"
#include "vtkCellArray.h"
#include "vtkDoubleArray.h"
#include "vtkMath.h"
vtkCxxRevisionMacro(vtkProjectedTerrainPath, "1.1");
// Begin vtkProjectedTerrainPath class implementation----------------------------
this->ProjectionMode = SIMPLE_PROJECTION;
this->HeightOffset = 10.0;
this->HeightTolerance = 10.0;
this->SubdivisionFactor = 1000;
this->LineError = NULL;
int vtkProjectedTerrainPath::RequestData(
vtkInformation *vtkNotUsed(request),
vtkInformationVector **vtkNotUsed(inputVector),
vtkInformationVector *vtkNotUsed(outputVector))
// get the info objects
// vtkInformation *inInfo = inputVector[0]->GetInformationObject(0);
// vtkInformation *outInfo = outputVector->GetInformationObject(0);
// get the input and ouptut
// vtkImageData *input = vtkImageData::SafeDownCast(
// inInfo->Get(vtkDataObject::DATA_OBJECT()));
// vtkPolyData *output = vtkPolyData::SafeDownCast(
// outInfo->Get(vtkDataObject::DATA_OBJECT()));
return 1;
int vtkProjectedTerrainPath::FillInputPortInformation(int, vtkInformation *info)
info->Set(vtkAlgorithm::INPUT_REQUIRED_DATA_TYPE(), "vtkImageData");
return 1;
void vtkProjectedTerrainPath::PrintSelf(ostream& os, vtkIndent indent)
os << indent << "Projection Mode: ";
if ( this->ProjectionMode == SIMPLE_PROJECTION )
os << "Simple Projection\n";
else if ( this->ProjectionMode == NONOCCLUDED_PROJECTION )
os << "Non-occluded Projection\n";
else //if ( this->ProjectionMode == HUG_PROJECTION )
os << "Hug Projection\n";
os << indent << "Height Offset: " << this->HeightOffset << "\n";
os << indent << "Subdivision Factor: " << this->SubdivisionFactor << "\n";
Program: Visualization Toolkit
Module: vtkProjectedTerrainPath.h
Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
All rights reserved.
See Copyright.txt or for details.
This software is distributed WITHOUT ANY WARRANTY; without even
PURPOSE. See the above copyright notice for more information.
// .NAME vtkProjectedTerrainPath - project a polyline onto a terrain
// .SECTION Description
// vtkProjectedTerrainPath projects an input polyline onto a terrain. (The
// terrain is defined by a 2D height image and is the second input to the
// filter.) The polyline projection is controlled via several modes as
// follows. 1) Simple mode projects the polyline points onto the terrain,
// taking into account the height offset instance variable. 2) Non-occluded
// mode insures that no parts of the polyline are occluded by the terrain
// (e.g. a line passes through a mountain). This may require recursive
// subdivision of the polyline. 3) Hug mode insures that the polyine points
// remain within a constant distance from the surface. This may also require
// recursive subdivision of the polyline. Note that both non-occluded mode
// and hug mode take into account the height offset, so it is possible to
// create paths that hug terrain a certain distance above it. To use this
// filter, define two inputs: 1) a polyline, and 2) an image whose scalar
// values represent a height field. Then specify the mode, and the height
// offset to use.
// An outline of the algorithm is as follows. The filter begins by projecting
// the polyline points to the image (offset by the specified height offset).
// If the mode is non-occluded or hug, then the maximum error along each line
// segment is computed and placed into a priority queue. Each line segment is
// then split at the point of maximum error, and the two new line segments
// are evaluated for maximum error. This process continues until the line is
// not occluded by the terrain (non-occluded mode) or satisfies the error on
// variation from the surface (hug mode). (Note this process is repeated for
// each polyline in the input).
// .SECTION Caveats
// This algorithm requires the entire input image to be in memory, hence it
// may not work for extremely large images.
// The input height image is assumed to be positioned in the x-y plane so the
// scalar value is the z-coordinate, height value.
// A priority queue is used so that the 1) the total number of line segments
// can be controlled, and 2) the algorithm can terminate when the errors in
// the queue are less than the specified error tolerance.
// .SECTION See Also
// vtkGreedyTerrainDecimation
#ifndef __vtkProjectedTerrainPath_h
#define __vtkProjectedTerrainPath_h
#include "vtkPolyDataAlgorithm.h"
class vtkPriorityQueue;
class VTK_HYBRID_EXPORT vtkProjectedTerrainPath : public vtkPolyDataAlgorithm
// Description:
// Standard methids for printing and determining type information.
void PrintSelf(ostream& os, vtkIndent indent);
// Description:
// Instantiate the class.
static vtkProjectedTerrainPath* New();
// Description:
// Determine how to control the projection process. Simple projection
// just projects the original polyline points. Non-occluded projection
// insures that the polyline does not intersect the terrain surface.
// Hug projection is similar o non-occulded projection except that
// produces a path that is nearly parallel to the terrain (within the
// user specified height tolerance).
void SetProjectionModeToSimple()
void SetProjectionModeToNonOccluded()
void SetProjectionModeToHug()
// Description:
// This is the height above (or below) the terrain that the projected
// path should be. Positive values indicate distances above the terrain;
// negative values indicate distances below the terrain.
// Description:
// This is the allowable variation in the altitude of the path
// with respect to the variation in the terrain. It only comes
// into play if the hug projection mode is enabled.
// Description:
// This instance variable can be used to limit the total amount of
// line segments created during subdivision. A value of two will
// limit the total number of line segments in the polyline to
// two times the original number. Note that this does not mean that
// each line segment will be subdivided the number of times indicated
// since the polylines are subdivided based on maximum error.
virtual int RequestData(vtkInformation *, vtkInformationVector **,
vtkInformationVector *);
virtual int FillInputPortInformation(int port, vtkInformation *info);
//ivars that the API addresses
int ProjectionMode;
double HeightOffset;
double HeightTolerance;
int SubdivisionFactor;
//Bookeeping arrays
vtkPriorityQueue *LineError; //errors for each pt in height field
vtkProjectedTerrainPath(const vtkProjectedTerrainPath&); // Not implemented.
void operator=(const vtkProjectedTerrainPath&); // Not implemented.
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