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cgmap_gshhs.pro
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cgmap_gshhs.pro
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; docformat = 'rst'
;
; PURPOSE:
;
; Uses files from the Globally Self-consistent Hierarchical High-resolution Shoreline
; (GSHHS) data base to draw shorelines in the manner of MAP_CONTINENTS. In other words,
; it is assumed that a map coordinate data space has been established prior to calling
; this routine. See the example below. The GSHHS data files are
; `available for downloading <http://www.ngdc.noaa.gov/mgg/shorelines/gshhs.html>`.
; An `article describing how to use this program <http://www.idlcoyote.com/map_tips/gshhs.html>`
; is also available.
;
; Note, the authors of the GSHHS software *continually* change the header
; structure, which you MUST know to read the data file. There are are now
; at least four different structures in common use. Please find the one
; you need from the commented list below. The current code uses the structure
; for the 2.2 version of the GSHHS software.
;
;******************************************************************************************;
; ;
; Copyright (c) 2011, by Fanning Software Consulting, Inc. All rights reserved. ;
; ;
; Redistribution and use in source and binary forms, with or without ;
; modification, are permitted provided that the following conditions are met: ;
; ;
; * Redistributions of source code must retain the above copyright ;
; notice, this list of conditions and the following disclaimer. ;
; * Redistributions in binary form must reproduce the above copyright ;
; notice, this list of conditions and the following disclaimer in the ;
; documentation and/or other materials provided with the distribution. ;
; * Neither the name of Fanning Software Consulting, Inc. nor the names of its ;
; contributors may be used to endorse or promote products derived from this ;
; software without specific prior written permission. ;
; ;
; THIS SOFTWARE IS PROVIDED BY FANNING SOFTWARE CONSULTING, INC. ''AS IS'' AND ANY ;
; EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES ;
; OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT ;
; SHALL FANNING SOFTWARE CONSULTING, INC. BE LIABLE FOR ANY DIRECT, INDIRECT, ;
; INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED ;
; TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; ;
; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ;
; ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT ;
; (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS ;
; SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. ;
;******************************************************************************************;
;
;+--------------------------------------------------------------------------
; The program uses files from the Globally Self-consistent Hierarchical High-resolution Shoreline
; (GSHHS) data base to draw shorelines in the manner of MAP_CONTINENTS. In other words,
; it is assumed that a map coordinate data space has been established prior to calling
; this routine. See the example below. The GSHHS data files are
; `available for downloading <http://www.ngdc.noaa.gov/mgg/shorelines/gshhs.html>`.
; An `article describing how to use this program <http://www.idlcoyote.com/map_tips/gshhs.html>`
; is also available.
;
; Note, the authors of the GSHHS software *continually* change the header
; structure, which you MUST know to read the data file. There are are now
; at least four different structures in common use. Please find the one
; you need from the commented list in the code itself. The current code uses the structure
; for the 2.2 version of the GSHHS software.
;
; I have noticed that the polygon areas in the 2.2 version of the GSHHS software seem
; to contain completely bogus information. For example, the Great Lakes polygon is 1.7e7
; square kilometers, while a tiny lake near-by is listed as 3.5e7 square kilometers. I have
; no explanation for why these values seem to be so wrong. I haven't tested this on other
; GSHHS versions of the data.
;
; :Categories:
; Graphics, Map Projections
;
; :Params:
; filename: in, optional, type=string
; The name of the GSHHS file to open. If not provided, the user will
; be asked to select the file with a file selection tool.
;
; :Keywords:
; addcmd: in, optional, type=boolean, default=0
; If this keyword is set, the object is added to the resizeable graphics
; window, cgWindow. Note that a map projection command must be
; added to the window before this command is added to be effective.
; color: in, optional, type=string, default="opposite"
; The name of the drawing color.
; fill: in, optional, type=boolean, default=0
; Set this keyword to draw filled outlines.
; land_color: in, optional, type=string, default="tan8"
; The name of the land color (for FILL).
; level: in, optional, type=integer, default=2
; The polygon LEVEL. All polygons less than or equal to this value
; are drawn. 1-land, 2-lakes, 3-island in lake, 4-pond in island.
; By default, 2 (land and lake outlines).
; map_structure: in, optional, type=varies
; A map projection structure (as created from MAP_PROJ_INIT) or a map coordinate
; object (i.e., cgMap). If using a map projection structure, a map coordinate system
; must be set up for the entire display window.
; minarea: in, optional, type=float, default=500
; The minimum feature area in square kilometers. Features with area below
; the minimum area will not be drawn on the map.
; noclip: in, optional, type=boolean, default=0
; Normally the polygons and outlines are clipped to the plot boundaries.
; Set this keyword to turn this feature off.
; outline: in, optional, type=boolean
; Set this keyword to draw outlines on filled polygons. Set to 1, by default,
; if FILL=0. Set to zero to not draw outlines on filled polygons.
; thick: in, optional, type=integer, default=!P.Thick
; Set this keyword to the thickness of the lines that are drawn.
; water_color: in, optional, type=string, default="sky blue"
; The name of color to draw water features in.
;
; :Author:
; FANNING SOFTWARE CONSULTING::
; David W. Fanning
; 1645 Sheely Drive
; Fort Collins, CO 80526 USA
; Phone: 970-221-0438 <
; E-mail: [email protected]
; Coyote's Guide to IDL Programming: http://www.idlcoyote.com
;
; :Examples:
; Example using cgMAP_SET to set up the map coordinate space::
;
; datafile = 'gshhs_h.b'
; cgDisplay, 500, 350
; pos = [0.1,0.1, 0.9, 0.8]
; cgMap_Set, -25.0, 135.0, Position=pos, /Mercator, Scale=64e6, Color='black'
; cgColorfill, [pos[0], pos[0], pos[2], pos[2], pos[0]], $
; [pos[1], pos[3], pos[3], pos[1], pos[1]], $
; /Normal, Color='sky blue'
; cgMap_GSHHS, datafile, Fill=1, Level=3, Color='black', /Outline
; cgText, 0.5, 0.85, 'Australia', Font=0, Color='black', /Normal, Alignment=0.5
; cgPlotS, [pos[0], pos[0], pos[2], pos[2], pos[0]], $
; [pos[1], pos[3], pos[3], pos[1], pos[1]], $
; /Normal, Color='black', Thick=2
;
; Example using MAP_PROJ_INIT to set up the map coordinate space::
;
; datafile = 'gshhs_h.b'
; cgDisplay
; map = Obj_New('cgMap', "Lambert Azimuthal", Limit=[40, -95, 50, -75], $
; Center_Lat=45, Center_Lon=-85)
; map -> SetProperty, Position=[0.1, 0.1, 0.90, 0.75], /Draw
; cgMap_GSHHS, datafile, /Fill, Level=3, Map_Structure=map, $
; Water='DODGER BLUE'
; cgMap_Grid, /Label, /Box, Color='charcoal', Map_Structure=map
; cgMap_Continents, /USA, Map_Structure=map
; cgText, 0.5, 0.85, 'Great Lakes Region', Font=0, Color='charcoal', $
; /Normal, Alignment=0.5
;
; :History:
; Modification History::
; Written by David W. Fanning, from Map_GSHHS_Shoreline program, 12 November 2011.
; Added THICK keyword. 28 Dec 2011. DWF.
; Modified so you can pass a map object with the MAP_STRUCTURE keyword and not
; have it change the object to a structure. 5 April 2012. DWF.
; Updated to use the polygon magnitude factor when calculating polygon area that
; was introduced in GSSHG 2.2. 22 Nov 2013. DWF.
;
; :Copyright:
; Copyright (c) 2011, Fanning Software Consulting, Inc.
;---------------------------------------------------------------------------
PRO cgMap_GSHHS, filename, $ ; The name of the GSHHS data file to open
ADDCMD=addcmd, $ ; Add this command to a resizeable graphics window.
COLOR=color, $ ; The name of the drawing color.
FILL=fill, $ ; Set this keyword to draw filled outlines.
LAND_COLOR=land_color, $ ; The name of the land color (for FILL).
LEVEL=level, $ ; The polygon LEVEL.
MAP_STRUCTURE=map_structure, $ ; A map projection structure (from MAP_PROJ_INIT).
MINAREA=minarea, $ ; The minimum feature area. By default, 500 km^2.
NOCLIP=noclip, $ ; Clip the polygons and lines to the plot boundaries.
OUTLINE=outline, $ ; Set this keyword to draw shorelines. Set by default if FILL=0.
THICK=thick, $ ; The thickness of the line that is drawn.
WATER_COLOR=water_color ; The name of the water color.
; Error handling.
Catch, theError
IF theError NE 0 THEN BEGIN
Catch, /Cancel
void = cgErrorMsg()
IF N_Elements(lun) NE 0 THEN Free_Lun, lun
IF N_Elements(thisState) NE 0 THEN cgSetColorState, thisState
IF N_Elements(r) NE 0 THEN TVLCT, r, g, b
RETURN
ENDIF
IF Keyword_Set(addcmd) THEN BEGIN
cgWindow, 'cgMap_GSHHS', filename, $ ; The name of the GSHHS data file to open
COLOR=color, $ ; The name of the drawing color.
FILL=fill, $ ; Set this keyword to draw filled outlines.
LAND_COLOR=land_color, $ ; The name of the land color (for FILL).
LEVEL=level, $ ; The polygon LEVEL.
MAP_STRUCTURE=map_structure, $ ; A map projection structure (from MAP_PROJ_INIT).
MINAREA=minarea, $ ; The minimum feature area. By default, 500 km^2.
OUTLINE=outline, $ ; Set this keyword to draw shorelines. Set by default if FILL=0.
THICK=thick, $ ; The thickness of the line that is drawn.
WATER_COLOR=water_color, $ ; The name of the water color.
ADDCMD=1
RETURN
ENDIF
; Do this in decomposed color mode if possible.
cgSetColorState, 1, CurrentState=thisState
TVLCT, r, g, b, /Get
; Default values.
IF N_Elements(filename) EQ 0 THEN BEGIN
filename = Dialog_Pickfile(Filter='*.b', Title='Select GSHHS File...')
IF filename EQ "" THEN RETURN
ENDIF
; Make sure the filename exists.
IF ~File_Test(filename, /Read) THEN Message, 'Cannot find or read the file ' + filename + '.'
IF Keyword_Set(fill) THEN temp_outline = 0 ELSE temp_outline = 1
fill = Keyword_Set(fill)
; If you are doing graphics on a display device and there is no window
; open one so you can do Convert_Coord correctly.)
IF (!D.Name EQ 'WIN') || (!D.Name EQ 'X') && (!D.Window LT 0) THEN cgDisplay
; If you got a map object, use it to recover a map structure
; and to set up the map coordinate space.
IF N_Elements(map_structure) NE 0 THEN BEGIN
IF Obj_Valid(map_structure) THEN BEGIN
mapObj = map_structure
mapStruct = mapObj -> GetMapStruct()
mapObj -> Draw, /NoGraphics
ENDIF ELSE mapStruct = map_structure
ENDIF
IF N_Elements(outline) EQ 0 THEN outline = temp_outline ELSE outline = Keyword_Set(outline)
IF N_Elements(level) EQ 0 THEN level = 2 ELSE level = 1 > level < 4
SetDefaultValue, minArea, 500.0 ; square kilometers.
noclip = Keyword_Set(noclip)
SetDefaultValue, color, 'opposite'
SetDefaultValue, water_color, 'sky blue'
SetDefaultValue, land_color, 'tan8'
SetDefaultValue, thick, !P.Thick
; Open the GSHHS data file.
OPENR, lun, filename, /Get_Lun, /Swap_If_Little_Endian
; ; Define the polygon header. This is for versions of the GSHHS software of 1.3 and earlier.
; header = { id: 0L, $ ; A unique polygon ID number, starting at 0.
; npoints: 0L, $ ; The number of points in this polygon.
; polygonLevel: 0L, $ ; 1 land, 2 lake, 3 island-in-lake, 4 pond-in-island.
; west: 0L, $ ; West extent of polygon boundary in micro-degrees.
; east: 0L, $ ; East extent of polygon boundary in micro-degrees.
; south: 0L, $ ; South extent of polygon boundary in micro-degrees.
; north: 0L, $ ; North extent of polygon boundary in micro-degrees.
; area: 0L, $ ; The area of polygon in 1/10 km^2.
; version: 0L, $ ; Polygon version, always set to 3 in this version.
; greenwich: 0S, $ ; Set to 1 if Greenwich median is crossed by polygon.
; source: 0S } ; Database source: 0 WDB, 1 WVS.
; Define the polygon header, for GSHHS software 1.4 through 1.11, which uses a 40 byte
; header structure. For example, gshhs_i.b from the gshhs_1.10.zip file.
; header = { id: 0L, $ ; A unique polygon ID number, starting at 0.
; npoints: 0L, $ ; The number of points in this polygon.
; flag: 0L, $ ; Contains polygonlevel, version, greenwich, and source values.
; west: 0L, $ ; West extent of polygon boundary in micro-degrees.
; east: 0L, $ ; East extent of polygon boundary in micro-degrees.
; south: 0L, $ ; South extent of polygon boundary in micro-degrees.
; north: 0L, $ ; North extent of polygon boundary in micro-degrees.
; area: 0L, $ ; Database source: 0 WDB, 1 WVS.
; junk:bytarr(8)} ; Eight bytes of junk to pad header.
; Define the polygon header, for GSHHS software 1.4 through 1.11, which uses a 32 byte
; header structure. For example, gshhs_h.b from the gshhs_1.11.zip.
; header = { id: 0L, $ ; A unique polygon ID number, starting at 0.
; npoints: 0L, $ ; The number of points in this polygon.
; flag: 0L, $ ; Contains polygonlevel, version, greenwich, and source values.
; west: 0L, $ ; West extent of polygon boundary in micro-degrees.
; east: 0L, $ ; East extent of polygon boundary in micro-degrees.
; south: 0L, $ ; South extent of polygon boundary in micro-degrees.
; north: 0L, $ ; North extent of polygon boundary in micro-degrees.
; area: 0L} ; Database source: 0 WDB, 1 WVS.
; Define the polygon header, for GSHHS software 2.0, which uses a 44 byte
; header structure. For example, gshhs_h.b from the gshhs_2.0.zip.
; header = { id: 0L, $ ; A unique polygon ID number, starting at 0.
; npoints: 0L, $ ; The number of points in this polygon.
; flag: 0L, $ ; Contains polygon level, version, greenwich, source, and river values.
; west: 0L, $ ; West extent of polygon boundary in micro-degrees.
; east: 0L, $ ; East extent of polygon boundary in micro-degrees.
; south: 0L, $ ; South extent of polygon boundary in micro-degrees.
; north: 0L, $ ; North extent of polygon boundary in micro-degrees.
; area: 0L, $ ; Area of polygon in 1/10 km^2.
; area_full: 0L, $ ; Area of origiinal full-resolution polygon in 1/10 km^2.
; container: 0L, $ ; ID of container polygon that encloses this polygon (-1 if "none").
; ancestor: 0L } ; ID of ancestor polygon in the full resolution set that was the source
; ; of this polygon (-1 of "none").
;
; I don't have a polygon header for version 2.1 of the GSHHS software but I believe the 2.0 header will
; work. This version of GSHHS was pretty buggy and not used very long. Better to upgrade to 2.2.
;
; Define the polygon header, for GSHHS software 2.2, which uses a 44 byte
; header structure. For example, gshhs_h.b from the gshhg_2.2.zip.
header = { id: 0L, $ ; A unique polygon ID number, starting at 0.
npoints: 0L, $ ; The number of points in this polygon.
flag: 0L, $ ; Bytes defined as:
; 1st byte: level = flag & 255: Values: 1 land, 2 lake, 3 island_in_lake, 4 pond_in_island_in_lake
; 2nd byte: version = (flag >> 8) & 255: Values: Should be 9 for GSHHS release 9
; 3rd byte: greenwich = (flag >> 16) & 3: Values: 0 if Greenwich nor Dateline are crossed,
; 1 if Greenwich is crossed, 2 if Dateline is crossed, 3 if both is crossed.
; 4th byte: source = (flag >> 24) & 1: Values: 0 = CIA WDBII, 1 = WVS
; 5th byte: river = (flag >> 25) & 1: Values: 0 = not set, 1 = river-lake and GSHHS level = 2 (or WDBII class 0)
; 6th byte: area magnitude scale p (as in 10^p) = flag >> 26. We divide area by 10^p.
west: 0L, $ ; West extent of polygon boundary in micro-degrees.
east: 0L, $ ; East extent of polygon boundary in micro-degrees.
south: 0L, $ ; South extent of polygon boundary in micro-degrees.
north: 0L, $ ; North extent of polygon boundary in micro-degrees.
area: 0L, $ ; Area of polygon in area/10^p = km^2.
area_full: 0L, $ ; Area of original full-resolution polygon in area_full/10^p = km2.
container: 0L, $ ; ID of container polygon that encloses this polygon (-1 if "none").
ancestor: 0L } ; ID of ancestor polygon in the full resolution set that was the source
; of this polygon (-1 of "none").
; Read the data and plot if required.
count = 0L
WHILE (EOF(lun) NE 1) DO BEGIN
READU, lun, header
; Parse the flag. Version 6 corresponds to 1.1x. Version 7 corresponds to 2.0.
; Version 8 corresponds to 2.1 and Version 9 corresponds to 2.2.
f = header.flag
version = ISHFT(f, -8) AND 255B
IF version LT 9 THEN BEGIN
IF version LE 3 THEN polygonLevel = header.level ELSE polygonLevel = (f AND 255B)
greenwich = ISHFT(f, -16) AND 1B
source = ISHFT(f, -24) AND 1B
river = ISHFT(f, -25) AND 1B
ENDIF ELSE BEGIN
polygonLevel = (f AND 255B)
greenwich = ISHFT(f, -16) AND 3B
source = ISHFT(f, -24) AND 1B
river = ISHFT(f, -25) AND 1B
magnitude = ISHFT(f, -26) AND 255B ; Divide header.area by 10^magnitude to get true area.
ENDELSE
; Get the polygon coordinates. Convert to lat/lon.
polygon = LonArr(2, header.npoints, /NoZero)
READU, lun, polygon
lon = Reform(polygon[0,*] * 1.0e-6)
lat = Reform(polygon[1,*] * 1.0e-6)
Undefine, polygon
; Discriminate polygons based on header information.
IF version LE 8 THEN BEGIN
polygonArea = Double(header.area) * 0.1 ; km^2
ENDIF ELSE BEGIN
polygonArea = Double(header.area) / 10.0^magnitude ; km^2
ENDELSE
IF polygonLevel GT level THEN CONTINUE
IF polygonArea LE minArea THEN CONTINUE
; If you have a MAP_STRUCTURE variable, use it to warp LAT/LON coordinates.
; No point in displaying polygons that are completely outside plot
; area set up by a map projection (MAP_SET) or some other plotting
; command.
IF N_Elements(mapStruct) NE 0 THEN BEGIN
; Convert lons from -180 to 180 to 0 to 360.
lon = ((lon + 180) MOD 360) - 180
;lon = (lon + 360.0) MOD 360.0
xy = Map_Proj_Forward(lon, lat, MAP_STRUCTURE=mapStruct)
lon = Reform(xy[0,*])
lat = Reform(xy[1,*])
ENDIF
xy = Convert_Coord(lon, lat, /Data, /To_Normal)
check = ((xy[0,*] GE !X.Window[0]) AND (xy[0,*] LE !X.Window[1])) AND $
((xy[1,*] GE !Y.Window[0]) AND (xy[1,*] LE !Y.Window[1]))
usePolygon = Max(check)
IF usePolygon EQ 0 THEN CONTINUE
; Draw polygons. Outlines drawn with PLOTS, filled polygons drawn with
; POLYFILL. Assumes lat/lon data coordinate space and colors are set up.
IF Keyword_Set(fill) THEN BEGIN
IF (polygonLevel EQ 1) OR (polygonLevel EQ 3) THEN BEGIN
POLYFILL, lon, lat, Color=cgColor(land_color), NOCLIP=noclip
ENDIF ELSE BEGIN
POLYFILL, lon, lat, Color=cgColor(water_color), NOCLIP=noclip
ENDELSE
ENDIF ELSE BEGIN
PLOTS, lon, lat, Color=cgColor(color), NOCLIP=noclip, Thick=thick
ENDELSE
; Need outlines with a fill?
IF Keyword_Set(fill) AND Keyword_Set(outline) THEN $
PLOTS, lon, lat, Color=cgColor(color), NOCLIP=noclip, Thick=thick
ENDWHILE
Free_Lun, lun
; Restore decomposition state.
cgSetColorState, thisState
IF !D.NAME NE 'Z' THEN TVLCT, r, g, b
END