Line data    Source code

       1             : /******************************************************************************
       2             :  *
       3             :  * Project:  Viewshed Generation
       4             :  * Purpose:  Core algorithm implementation for viewshed generation.
       5             :  * Author:   Tamas Szekeres, szekerest@gmail.com
       6             :  *
       7             :  ******************************************************************************
       8             :  *
       9             :  * Permission is hereby granted, free of charge, to any person obtaining a
      10             :  * copy of this software and associated documentation files (the "Software"),
      11             :  * to deal in the Software without restriction, including without limitation
      12             :  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
      13             :  * and/or sell copies of the Software, and to permit persons to whom the
      14             :  * Software is furnished to do so, subject to the following conditions:
      15             :  *
      16             :  * The above copyright notice and this permission notice shall be included
      17             :  * in all copies or substantial portions of the Software.
      18             :  *
      19             :  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
      20             :  * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
      21             :  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
      22             :  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
      23             :  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
      24             :  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
      25             :  * DEALINGS IN THE SOFTWARE.
      26             :  ****************************************************************************/
      27             : 
      28             : #include <cstdint>
      29             : #include <memory>
      30             : #include <string>
      31             : 
      32             : #include "cpl_progress.h"
      33             : #include "gdal_priv.h"
      34             : 
      35             : namespace gdal
      36             : {
      37             : 
      38             : /**
      39             :  * Class to support viewshed raster generation.
      40             :  */
      41             : class Viewshed
      42             : {
      43             :   public:
      44             :     /**
      45             :      * Raster output mode.
      46             :      */
      47             :     enum class OutputMode
      48             :     {
      49             :         Normal,  //!< Normal output mode (visibility only)
      50             :         DEM,     //!< Output height from DEM
      51             :         Ground   //!< Output height from ground
      52             :     };
      53             : 
      54             :     /**
      55             :      * Cell height calculation mode.
      56             :      */
      57             :     enum class CellMode
      58             :     {
      59             :         Diagonal,  //!< Diagonal Mode
      60             :         Edge,      //!< Edge Mode
      61             :         Max,       //!< Maximum value produced by Diagonal and Edge mode
      62             :         Min        //!< Minimum value produced by Diagonal and Edge mode
      63             :     };
      64             : 
      65             :     /**
      66             :      * A point.
      67             :      */
      68             :     struct Point
      69             :     {
      70             :         double x;  //!< X value
      71             :         double y;  //!< Y value
      72             :         double z;  //!< Z value
      73             :     };
      74             : 
      75             :     /**
      76             :      * Options for viewshed generation.
      77             :      */
      78             :     struct Options
      79             :     {
      80             :         Point observer{0, 0, 0};  //!< x, y, and z of the observer
      81             :         uint8_t visibleVal{255};  //!< raster output value for visible pixels.
      82             :         uint8_t invisibleVal{
      83             :             0};  //!< raster output value for non-visible pixels.
      84             :         uint8_t outOfRangeVal{
      85             :             0};  //!< raster output value for pixels outside of max distance.
      86             :         double nodataVal{-1};  //!< raster output value for pixels with no data
      87             :         double targetHeight{0.0};  //!< target height above the DEM surface
      88             :         double maxDistance{
      89             :             0.0};  //!< maximum distance from observer to compute value
      90             :         double curveCoeff{.85714};  //!< coefficient for atmospheric refraction
      91             :         OutputMode outputMode{OutputMode::Normal};  //!< Output information.
      92             :             //!< Normal, Height from DEM or Height from ground
      93             :         std::string outputFormat{};    //!< output raster format
      94             :         std::string outputFilename{};  //!< output raster filename
      95             :         CPLStringList creationOpts{};  //!< options for output raster creation
      96             :         CellMode cellMode{
      97             :             CellMode::Edge};  //!< Mode of cell height calculation.
      98             :     };
      99             : 
     100             :     /**
     101             :      * Constructor.
     102             :      *
     103             :      * @param opts Options to use when calculating viewshed.
     104             :     */
     105          12 :     CPL_DLL explicit Viewshed(const Options &opts) : oOpts{opts}, poDstDS{}
     106             :     {
     107          12 :     }
     108             : 
     109             :     /**
     110             :      * Create the viewshed for the provided raster band.
     111             :      *
     112             :      * @param hBand  Handle to the raster band.
     113             :      * @param pfnProgress  Progress reporting callback function.
     114             :      * @param pProgressArg  Argument to pass to the progress callback.
     115             :     */
     116             :     CPL_DLL bool run(GDALRasterBandH hBand, GDALProgressFunc pfnProgress,
     117             :                      void *pProgressArg = nullptr);
     118             : 
     119             :     /**
     120             :      * Fetch a pointer to the created raster band.
     121             :      *
     122             :      * @return  Unique pointer to the viewshed dataset.
     123             :     */
     124          12 :     CPL_DLL std::unique_ptr<GDALDataset> output()
     125             :     {
     126          12 :         return std::move(poDstDS);
     127             :     }
     128             : 
     129             :   private:
     130             :     Options oOpts;
     131             :     std::unique_ptr<GDALDataset> poDstDS;
     132             : 
     133             :     void setVisibility(int iPixel, double dfZ, double *padfZVal,
     134             :                        std::vector<GByte> &vResult);
     135             :     double calcHeight(double dfZ, double dfZ2);
     136             : };
     137             : 
     138             : }  // namespace gdal