Rename tgSplitPolygon() -> tgChopPolygon() which is slightly more descriptive

and doesn't sound so much like the split long edges function.

README

@@ -1,75 +1,164 @@
-FG Scenery Tools README
+TerraGear Scenery Tools README
-=======================
+==============================
 
-Contained here-in are the FG scenery creation tools.  These can be
+TerraGear is a collection of tools for building scenery for the
-used to convert 3 arcsec ASCII format DEM files and 30 arcsec binary
+FlightGear project.  Generally, the process is done in two steps:
-format DEM files into Flight Gear scenery.
 
-Eventually these tools will expand to support insertion of airports,
+  1. Preprocess the original raw data.  This chops up the data into
-roads, rivers, lakes, etc.
+     the FG tiling scheme and saves it in a simple, intermediate
+     format.
+
+  2. Collect all the different pieces of intermediate data and
+     assemble them into a 3d model of the terrain.
+
+There is currently no graphical front end for these tools so you will
+need to run them from the command line.  Be prepaired, when building
+scenery on a world wide scale, be prepaired to burn through multiple
+gigabytes of disk space and days or weeks of crunching.  Building
+smaller chunks is much more doable though.
 
 
 Building the Tools
 ==================
 
-These tools are compiled and tested under Linux.  I'm all for
+These tools are primarily compiled and tested under Unix with the gnu
-portability, but I just haven't been as motivated to port these tools,
+compilers.  I believe they also build and run on windows with Cygwin.
-since scenery creation is less of a general need ... especially at
+If anyone has patches for supporting other platforms, I will be happy
-this stage.  However, if anyone wants to work on porting to other
+to incorporate them.
-platforms, I will be happy to incorporate patches.
 
 The process for building these tools is very similar to building the
 main FG source code.
 
-1.  Set the FG_ROOT, FG_ROOT_SRC, and FG_ROOT_LIB environment
+1.  If you are using the CVS version of the source, run the
-    variables.
+    "autogen.sh" script.  If you downloaded the source tarball, then
+    don't.
 
-2.  Run ``make depend''
+2.  Run the "configure" script, with optional arguments for setting
+    the install prefix, etc..
 
-3.  Run ``make clean''
+3.  Run "make"
 
-4.  Run ``make''
+4.  Run "make install"
 
 
-3 Arcsec ASCII DEM files
+Preprocessing Terrain
-========================
+=====================
 
-Data files for the USA are available in this format from:
+TerraGear supports several terrain data sources:
 
-    http://edcwww.cr.usgs.gov/doc/edchome/ndcdb/ndcdb.html
+1. 30-arcsec SRTM based terrain data covering the world (recommended
+   over other 30-arcsec data sources):
 
-To generate FG scenery from one of these dem files, run:
+   ftp://edcsgs9.cr.usgs.gov/pub/data/srtm/SRTM30/
 
-    ./process-dem.pl <error-tolerance-squared> dem-file-1 [ dem-file-2 ...]
+   I don't recall the details at the moment for processing this data.
+   Probably similar to the processing of the GLOBE data.
 
-You can vary the error tolerance to control the level of detail (and
+2. 30-arcsec world wide data: GLOBE project:
-size) of the resulting scenery.  Note, you must specify the error
-tolerance squared.  So, if you wish to allow up to a 10 meter error
-margin (very high level of detail) you would specify a value of 100.
-If you desire an error tolerance of 200 meters (medium detail level)
-you would specify a value of 40000.
 
-The process-dem.pl script will automatically dump the resulting .obj
+   http://www.ngdc.noaa.gov/seg/topo/globe.shtml
-files in the proper directory tree.
+
+   a) First convert the "bin" DEM format to "ascii" DEM format using
+      "Prep/DemRaw2ascii/raw2ascii"
+
+   b) Then process the resulting files with "Prep/DemChop/demchop"
 
 
-30 Arcsec Binary DEM files
+3. 30-arcsec world wide data: GTOPO30 data:
-==========================
 
-These data files have world wide coverage and are available from:
+   http://edcwww.cr.usgs.gov/landdaac/gtopo30/gtopo30.html
 
-    http://edcwww.cr.usgs.gov/landdaac/gtopo30/gtopo30.html
+   a) First convert the "bin" DEM format to "ascii" DEM format using
+      "Prep/DemRaw2ascii/raw2ascii"
 
-To process these data files, you must first run:
+   b) Then process the resulting files with "Prep/DemChop/demchop"
 
-    DemRaw2Ascii/raw2ascii <input_file_basename> <output_dir>
 
-For example:
+4. SRTM (1 and 3-arcsec nearly world wide coverage):
 
-    DemRaw2Ascii/raw2ascii /tmp/W020N90 asciidems/ 
+   ftp://edcsgs9.cr.usgs.gov/pub/data/srtm/
 
-This will create ASCII DEM files for each 1 degree x 1 degree area in
+   a) Chop up the .zip files using "Prep/DemChop/hgtchop"
-the specified output dir.
 
-Then, you can take these ascii dem files and feed them through the
+
-same procedure you use with the 3 arcsec dem files.
+5. 3-arcsec ASCII DEM files:
+
+   Generally, I recommend using the SRTM data over this older data
+   set, however in places like Alaska, there is no SRTM coverage so
+   this data is better than the 30 arcsec data.
+
+       http://edcwww.cr.usgs.gov/doc/edchome/ndcdb/ndcdb.html
+
+   a) Create the .arr.gz files using the "Prep/DemChop/demchop" utility.
+
+
+The result for any of these terrain sources should be a "work" tree
+with a .arr.gz file for each FG tile.
+
+6. After you create the .arr.gz files you have to create a
+   corresponding .fit.gz file for each of these.  This is a data
+   reduction step which fits a set of polygons to the raw terrain with
+   a set of constraints on the maximum error allowed relative to the
+   original data set, and a max/min number of allowed nodes in the
+   fitted set.  The provided tools use a scheme that produces an
+   adaptive fit which means fewer polygons in smooth flat areas, and
+   more polygons in complex rough areas.  The end result is a *much*
+   better fit with fewer polygons than you could achieve by just keeping
+   every "nth" point from the original array.
+
+   To walk through an entire tree of .arr.gz files and produce the
+   corresponding .fit.gz files, use the "Prep/TerraFit/terrafit.py"
+   utility.  Please ignore the old "ArrayFit" tools which use a stupid
+   algorithm and are basically useless in comparison to TerraFit.
+   
+
+You should now have a large tree of .arr.gz files with a corresponding
+.fit.gz file for each .arr.gz file.  It's worth double checking the
+contents of your directory and counting all files of each type to make
+sure you do have a one to one match and didn't miss anything.
+
+
+Generating Airports
+===================
+
+Robin Peel maintains a world wide database of airports and navaids for
+the X-Plane and FlightGear projects:
+
+    http://www.x-plane.org/users/robinp/
+
+Robin's apt.dat needs to be run through two scripts
+
+    cat apt.dat | ./xp2simpleapt.pl > basic.dat
+    cat apt.dat | ./xp2runway.pl > runways.dat
+
+Compress these and copy them to $FG_ROOT/data/Airports
+
+Now run the runways.dat through the getapt utility:
+
+    genapts --input=runways.dat --work=$FG_WORK_DIR
+
+Note: this creates a last_apt file which shows you the airport genapts
+is currently working on.
+
+    - if genapts crashes (which is possible if you try to run through the
+      entire runways.dat file) you can look at last_apt to see where to start
+      up again.
+
+    - You can start in midstream using the --start-id=KABC option to genapts.
+
+    - If you get a consistant crash on a particular airport, you probably
+      found a bug in genapts, or there is some degenerate information at that
+      airport (40 mile long runways, 2 runways spaced miles apart, etc.)
+      Often you can fix the data and proceed.  Sometimes you can "nudge"
+      things around to get past a genapts bug.  For instance, if you crahs
+      consistantly on a valid looking runway, try nudging the heading or
+      position by a least significant digit.  Sometimes we can get numerical
+      problems with the polygon cliper and this often works around it.
+
+Other considerations:
+
+    - Airport generation pre-depends on terrain data being preped and ready
+      so airport surfaces can be built properly.
+
+    - If you prep new terrain data, you should probably rerun the airport
+      generation step.

src/Airports/GenAirports/build.cxx

@@ -50,9 +50,9 @@
 #include <Geometry/poly_support.hxx>
 #include <Geometry/trinodes.hxx>
 #include <Output/output.hxx>
+#include <Polygon/chop.hxx>
 #include <Polygon/index.hxx>
 #include <Polygon/polygon.hxx>
-#include <Polygon/split.hxx>
 #include <Polygon/superpoly.hxx>
 #include <Triangulate/trieles.hxx>
 
@@ -1210,8 +1210,8 @@ void build_airport( string airport_id, float alt_m,
     string holepath = root + "/AirportArea";
     // long int poly_index = poly_index_next();
     // write_boundary( holepath, b, hull, poly_index );
-    tgSplitPolygon( holepath, HoleArea, divided_base, true );
+    tgChopPolygon( holepath, HoleArea, divided_base, true );
-    tgSplitPolygon( holepath, AirportArea, apt_clearing, false );
+    tgChopPolygon( holepath, AirportArea, apt_clearing, false );
     
 }
 

src/Lib/Polygon/Makefile.am

@@ -1,11 +1,11 @@
 noinst_LIBRARIES = libPolygon.a
 
 libPolygon_a_SOURCES = \
+	chop-bin.cxx chop.hxx \
 	index.cxx index.hxx \
 	names.cxx names.hxx \
 	polygon.cxx polygon.hxx \
 	simple_clip.cxx simple_clip.hxx \
-	split-bin.cxx split.hxx \
 	superpoly.cxx superpoly.hxx
 
 INCLUDES = -I$(top_srcdir)/src -I$(top_srcdir)/src/Lib

src/Lib/Polygon/chop-bin.cxx

@@ -1,8 +1,10 @@
-// split.cxx -- polygon splitting utils
+// chop-bin.hxx -- routine to chop a polygon up along tile boundaries and
+//                 write the individual pieces to the TG working polygon
+//                 file format.
 //
 // Written by Curtis Olson, started February 1999.
 //
-// Copyright (C) 1999  Curtis L. Olson  - curt@flightgear.org
+// Copyright (C) 1999-2004  Curtis L. Olson  - curt@flightgear.org
 //
 // This program is free software; you can redistribute it and/or modify
 // it under the terms of the GNU General Public License as published by
@@ -20,6 +22,7 @@
 //
 // $Id$
 
+
 #ifdef HAVE_CONFIG_H
 #  include <config.h>
 #endif
@@ -39,7 +42,7 @@
 #include "index.hxx"
 #include "names.hxx"
 #include "simple_clip.hxx"
-#include "split.hxx"
+#include "chop.hxx"
 
 
 static void clip_and_write_poly( string root, long int p_index, AreaType area, 
@@ -144,9 +147,10 @@ static void clip_and_write_poly( string root, long int p_index, AreaType area,
 }
 
 
-// process shape (write polygon to all intersecting tiles)
+// process polygon shape (chop up along tile boundaries and write each
-void tgSplitPolygon( const string& path, AreaType area,
+// polygon piece to a file)
-                     const TGPolygon& shape, bool preserve3d )
+void tgChopPolygon( const string& path, AreaType area,
+                    const TGPolygon& shape, bool preserve3d )
 {
     Point3D min, max, p;
     // point2d min, max;
@@ -264,7 +268,7 @@ void tgSplitPolygon( const string& path, AreaType area,
 	    bottom_clip = horizontal_clip( shape, clip_line, Below );
 	}
 
-	tgSplitPolygon( path, area, bottom_clip, preserve3d );
+	tgChopPolygon( path, area, bottom_clip, preserve3d );
     }
 
     {
@@ -293,6 +297,6 @@ void tgSplitPolygon( const string& path, AreaType area,
 	    top_clip = horizontal_clip( shape, clip_line, Above );
 	}
 
-	tgSplitPolygon( path, area, top_clip, preserve3d );
+	tgChopPolygon( path, area, top_clip, preserve3d );
     }
 }

src/Lib/Polygon/chop.hxx

@@ -1,8 +1,10 @@
-// split.hxx -- polygon splitting utils
+// chop.hxx -- routine to chop a polygon up along tile boundaries and
+//             write the individual pieces to the TG working polygon
+//             file format.
 //
 // Written by Curtis Olson, started February 1999.
 //
-// Copyright (C) 1999  Curtis L. Olson  - curt@flightgear.org
+// Copyright (C) 1999-2004  Curtis L. Olson  - curt@flightgear.org
 //
 // This program is free software; you can redistribute it and/or modify
 // it under the terms of the GNU General Public License as published by
@@ -21,19 +23,20 @@
 // $Id$
 
 
-#ifndef _SPLIT_HXX
+#ifndef _TG_CHOP_HXX
-#define _SPLIT_HXX
+#define _TG_CHOP_HXX
 
 
 #include "names.hxx"
 #include "polygon.hxx"
 
 
-// process shape (write polygon to all intersecting tiles)
+// process polygon shape (chop up along tile boundaries and write each
-void tgSplitPolygon( const string& path, AreaType area,
+// polygon piece to a file)
-                     const TGPolygon& shape, bool preserve3d );
+void tgChopPolygon( const string& path, AreaType area,
+                    const TGPolygon& shape, bool preserve3d );
 
 
-#endif // _SPLIT_HXX
+#endif // _TG_CHOP_HXX
 
 

src/Prep/E00Lines/main.cxx

@@ -44,10 +44,10 @@ SG_USING_STD(vector);
 
 #include <Geometry/rectangle.hxx>
 #include <Geometry/util.hxx>
+#include <Polygon/chop.hxx>
 #include <Polygon/index.hxx>
 #include <Polygon/names.hxx>
 #include <Polygon/polygon.hxx>
-#include <Polygon/split.hxx>
 #include <e00/e00.hxx>
 
 #ifdef _MSC_VER
@@ -179,7 +179,7 @@ processPoints (const E00 &data, const tg::Rectangle &bounds,
     }
 
     tg::makePolygon(p, width, shape);
-    tgSplitPolygon(workDir, areaType, shape, false);
+    tgChopPolygon(workDir, areaType, shape, false);
   }
 }
 
@@ -242,7 +242,7 @@ processLines (const E00 &data, const tg::Rectangle &bounds,
     cout << "  Minimum angle: "
 	 << (shape.minangle_contour(0) * SGD_RADIANS_TO_DEGREES) << endl;
     
-    tgSplitPolygon(workDir, areaType, shape, false);
+    tgChopPolygon(workDir, areaType, shape, false);
   }
   cout << "Done lines" << endl;
 }
@@ -309,7 +309,7 @@ processPolygons (const E00 &data, const tg::Rectangle &bounds,
 					  0.0));
       }
     }
-    tgSplitPolygon(workDir, areaType, shape, false);
+    tgChopPolygon(workDir, areaType, shape, false);
   }
 }
 

src/Prep/GSHHS/gshhs_split.cxx

@@ -31,10 +31,10 @@
 #include <simgear/bucket/newbucket.hxx>
 #include <simgear/debug/logstream.hxx>
 
+#include <Polygon/chop.hxx>
 #include <Polygon/index.hxx>
 #include <Polygon/names.hxx>
 #include <Polygon/polygon.hxx>
-#include <Polygon/split.hxx>
 #include <Polygon/simple_clip.hxx>
 
 #include "gshhs_split.hxx"
@@ -86,13 +86,13 @@ void split_and_shift_chunk( const string& path, AreaType area,
     upper_shape.shift( -360, 0 );
 
     SG_LOG ( SG_GENERAL, SG_INFO, "Processing lower shape" );
-    tgSplitPolygon(path, area, lower_shape, false);
+    tgChopPolygon(path, area, lower_shape, false);
 
     SG_LOG ( SG_GENERAL, SG_INFO, "Processing center shape" );
-    tgSplitPolygon(path, area, center_shape, false);
+    tgChopPolygon(path, area, center_shape, false);
 
     SG_LOG ( SG_GENERAL, SG_INFO, "Processing upper shape" );
-    tgSplitPolygon(path, area, upper_shape, false);
+    tgChopPolygon(path, area, upper_shape, false);
 }
 
 

src/Prep/GSHHS/main.cxx

@@ -38,7 +38,6 @@
 #include <Polygon/index.hxx>
 #include <Polygon/names.hxx>
 #include <Polygon/polygon.hxx>
-#include <Polygon/split.hxx>
 
 #ifdef _MSC_VER
 #  include <Win32/mkdir.hpp>

src/Prep/Photo/photo.cxx

@@ -39,8 +39,8 @@
 #include <Array/array.hxx>
 #include <Geometry/trinodes.hxx>
 #include <Output/output.hxx>
+#include <Polygon/chop.hxx>
 #include <Polygon/index.hxx>
-#include <Polygon/split.hxx>
 #include <Polygon/polygon.hxx>
 
 SG_USING_STD(string);
@@ -329,7 +329,7 @@ int main( int argc, char **argv ) {
     poly_index_init( counter_file );
 
     string holepath = root + "/PhotoArea";
-    tgSplitPolygon( holepath, HoleArea, hole, false );
+    tgChopPolygon( holepath, HoleArea, hole, false );
 
     return 0;
 }

src/Prep/ShapeFile/noaa-decode.cxx

@@ -29,10 +29,10 @@
 
 #include <simgear/debug/logstream.hxx>
 
+#include <Polygon/chop.hxx>
 #include <Polygon/index.hxx>
 #include <Polygon/names.hxx>
 #include <Polygon/polygon.hxx>
-#include <Polygon/split.hxx>
 #include <shapelib/shapefil.h>
 
 #ifdef _MSC_VER
@@ -417,7 +417,7 @@ int main( int argc, char **argv ) {
 	    // holes are preserved
 
 	    area = get_area_type( force_area_type );
-	    tgSplitPolygon(work_dir, area, shape, false);
+	    tgChopPolygon(work_dir, area, shape, false);
 	} else if ( area == OceanArea ) {
 	    // interior of polygon is ocean, holes are islands
 
@@ -425,7 +425,7 @@ int main( int argc, char **argv ) {
 
 	    // Ocean data now comes from GSHHS so we want to ignore
 	    // all other ocean data
-	    // tgSplitPolygon(work_dir, area, shape, false);
+	    // tgChopPolygon(work_dir, area, shape, false);
 	} else if ( area == VoidArea ) {
 	    // interior is ????
 
@@ -437,7 +437,7 @@ int main( int argc, char **argv ) {
 		// exit(-1);
 	    }
 
-	    // tgSplitPolygon(work_dir, area, shape, false);
+	    // tgChopPolygon(work_dir, area, shape, false);
 	} else if ( area == NullArea ) {
 	    // interior is ????
 
@@ -449,9 +449,9 @@ int main( int argc, char **argv ) {
 		// exit(-1);
 	    }
 
-	    // tgSplitPolygon(work_dir, area, shape, false);
+	    // tgChopPolygon(work_dir, area, shape, false);
 	} else {
-	    tgSplitPolygon(work_dir, area, shape, false);
+	    tgChopPolygon(work_dir, area, shape, false);
 	}
     }
 

src/Prep/ShapeFile/shape-decode.cxx

@@ -29,10 +29,10 @@
 
 #include <simgear/debug/logstream.hxx>
 
+#include <Polygon/chop.hxx>
 #include <Polygon/index.hxx>
 #include <Polygon/names.hxx>
 #include <Polygon/polygon.hxx>
-#include <Polygon/split.hxx>
 #include <shapelib/shapefil.h>
 
 #ifdef _MSC_VER
@@ -299,7 +299,7 @@ int main( int argc, char **argv ) {
 	    // holes are preserved
 
 	    area = get_area_type( force_area_type );
-	    tgSplitPolygon(work_dir, area, shape, false);
+	    tgChopPolygon(work_dir, area, shape, false);
 	} else if ( area == OceanArea ) {
 	    // interior of polygon is ocean, holes are islands
 
@@ -307,7 +307,7 @@ int main( int argc, char **argv ) {
 
 	    // Ocean data now comes from GSHHS so we want to ignore
 	    // all other ocean data
-	    // tgSplitPolygon(work_dir, area, shape, false);
+	    // tgChopPolygon(work_dir, area, shape, false);
 	} else if ( area == VoidArea ) {
 	    // interior is ????
 
@@ -319,7 +319,7 @@ int main( int argc, char **argv ) {
 		// exit(-1);
 	    }
 
-	    // tgSplitPolygon(work_dir, area, shape, false);
+	    // tgChopPolygon(work_dir, area, shape, false);
 	} else if ( area == NullArea ) {
 	    // interior is ????
 
@@ -331,9 +331,9 @@ int main( int argc, char **argv ) {
 		// exit(-1);
 	    }
 
-	    // tgSplitPolygon(work_dir, area, shape, false);
+	    // tgChopPolygon(work_dir, area, shape, false);
 	} else {
-	    tgSplitPolygon(work_dir, area, shape, false);
+	    tgChopPolygon(work_dir, area, shape, false);
 	}
     }
 

src/Prep/TGVPF/tgvpf.cxx

@@ -44,10 +44,10 @@ SG_USING_STD(vector);
 
 #include <Geometry/line.hxx>
 #include <Geometry/util.hxx>
+#include <Polygon/chop.hxx>
 #include <Polygon/index.hxx>
 #include <Polygon/names.hxx>
 #include <Polygon/polygon.hxx>
-#include <Polygon/split.hxx>
 #include <vpf/vpf.hxx>
 
 #ifdef _MSC_VER
@@ -537,7 +537,7 @@ main (int argc, const char **argv)
           if ( max_segment > 1.0 ) {
               shape = tgPolygonSplitLongEdges( shape, max_segment );
           }
-	  tgSplitPolygon(work_dir, material_type, shape, false);
+	  tgChopPolygon(work_dir, material_type, shape, false);
 	}
       }
     }
@@ -550,7 +550,10 @@ main (int argc, const char **argv)
       if (mask.total_size() >= 3) {
 	cout << "Inverse polygon with " << mask.total_size() << " points in "
 	     << mask.contours() << " contour(s)" << endl;
-	tgSplitPolygon(work_dir, material_type, mask, false);
+        if ( max_segment > 1.0 ) {
+            mask = tgPolygonSplitLongEdges( mask, max_segment );
+        }
+	tgChopPolygon(work_dir, material_type, mask, false);
       } else {
 	cout << "Inverse polygon is empty" << endl;
       }

src/Prep/UserDef/tguserdef.cxx

@@ -9,10 +9,10 @@
 #include <simgear/structure/exception.hxx>
 
 #include <Geometry/util.hxx>
+#include <Polygon/chop.hxx>
 #include <Polygon/index.hxx>
 #include <Polygon/names.hxx>
 #include <Polygon/polygon.hxx>
-#include <Polygon/split.hxx>
 
 #include <stdlib.h>
 
@@ -65,7 +65,7 @@ add_point (SGPropertyNode_ptr node)
   TGPolygon poly;
   tg::makePolygon(p, node->getIntValue("width", 500), poly);
   poly = tgPolygonInt(poly, bounds_poly);
-  tgSplitPolygon(".", material, poly, false);
+  tgChopPolygon(".", material, poly, false);
 }
 
 static void
@@ -86,7 +86,7 @@ add_line (SGPropertyNode_ptr node)
   TGPolygon poly;
   tg::makePolygon(line, node->getIntValue("width", 10), poly);
   poly = tgPolygonInt(poly, bounds_poly);
-  tgSplitPolygon(".", material, poly, false);
+  tgChopPolygon(".", material, poly, false);
 }
 
 static void
@@ -108,7 +108,7 @@ add_polygon (SGPropertyNode_ptr node)
     poly.set_hole_flag(i, contour_node->getBoolValue("hole", false));
   }
   poly = tgPolygonInt(poly, bounds_poly);
-  tgSplitPolygon(".", material, poly, false);
+  tgChopPolygon(".", material, poly, false);
 }
 
 void