MtkSetRegionByLatLonExtent.c

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/*===========================================================================
=                                                                           =
=                        MtkSetRegionByLatLonExtent                         =
=                                                                           =
=============================================================================

                         Jet Propulsion Laboratory
                                   MISR
                               MISR Toolkit

            Copyright 2005, California Institute of Technology.
                           ALL RIGHTS RESERVED.
                 U.S. Government Sponsorship acknowledged.

============================================================================*/

#include "MisrSetRegion.h"
#include "MisrError.h"
#include "MisrUtil.h"
#include <string.h>
#ifndef _MSC_VER
#include <strings.h>
#endif
#include <stdlib.h>

MTKt_status MtkSetRegionByLatLonExtent(
  double ctr_lat_dd, 
  double ctr_lon_dd, 
  double lat_extent, 
  double lon_extent, 
  const char *extent_units,
  MTKt_Region *region  )
{
  MTKt_status status_code;      /* Return code of this function */
  MTKt_Region rgn;      /* Region structure */
  double resolution;        /* Resolution */
  char *endptr;         /* End ptr for strod */

  if (region == NULL)
    MTK_ERR_CODE_JUMP(MTK_NULLPTR);

  /* Check extent_units */
  if (extent_units == NULL)
    MTK_ERR_CODE_JUMP(MTK_NULLPTR);

  /* Check latitude bounds */
  if (ctr_lat_dd > 90.0 || ctr_lat_dd < -90.0)
    MTK_ERR_CODE_JUMP(MTK_OUTBOUNDS);
  if (lat_extent <= 0.0)
    MTK_ERR_CODE_JUMP(MTK_OUTBOUNDS);

  /* Check longitude bounds */
  if (ctr_lon_dd > 180.0 || ctr_lon_dd < -180.0)
    MTK_ERR_CODE_JUMP(MTK_OUTBOUNDS);
  if (lon_extent <= 0.0)
    MTK_ERR_CODE_JUMP(MTK_OUTBOUNDS);

  /* Set center of region */
  rgn.geo.ctr.lat = ctr_lat_dd;
  rgn.geo.ctr.lon = ctr_lon_dd;

  /* Set half of the overall extent of region in specified units measured from center */
  if (strncasecmp(extent_units, "degrees", strlen(extent_units)) == 0 ||
      strncasecmp(extent_units, "deg", strlen(extent_units)) == 0 ||
      strncasecmp(extent_units, "dd", strlen(extent_units)) == 0) {

    /* Average earth circumference (40075004m + 39940638m) / 2.0 = 40007821m */
    double meters_per_deg = 40007821.0 / 360.0;
    rgn.hextent.xlat = (lat_extent * meters_per_deg) / 2.0;
    rgn.hextent.ylon = (lon_extent * meters_per_deg) / 2.0;

  } else if (strncasecmp(extent_units, "meters", strlen(extent_units)) == 0 ||
         strncasecmp(extent_units, "m", strlen(extent_units)) == 0) {

    rgn.hextent.xlat = lat_extent / 2.0;
    rgn.hextent.ylon = lon_extent / 2.0;

  } else if (strncasecmp(extent_units, "kilometers", strlen(extent_units)) == 0 ||
          strncasecmp(extent_units, "km", strlen(extent_units)) == 0) {

    rgn.hextent.xlat = (lat_extent * 1000) / 2.0;
    rgn.hextent.ylon = (lon_extent * 1000) / 2.0;

  } else if ((resolution = strtod(extent_units, &endptr)) != 0) {

    if (strncasecmp(endptr, "meters", strlen(endptr)) == 0  ||
    strncasecmp(endptr, "m", strlen(endptr)) == 0  ||
    strncasecmp(endptr, " meters", strlen(endptr)) == 0  ||
    strncasecmp(endptr, " m", strlen(endptr)) == 0) {

      rgn.hextent.xlat = (lat_extent * resolution) / 2.0;
      rgn.hextent.ylon = (lon_extent * resolution) / 2.0;

    } else if (strncasecmp(endptr, "kilometers", strlen(endptr)) == 0  ||
    strncasecmp(endptr, "km", strlen(endptr)) == 0  ||
    strncasecmp(endptr, " kilometers", strlen(endptr)) == 0  ||
    strncasecmp(endptr, " km", strlen(endptr)) == 0) {

      rgn.hextent.xlat = (lat_extent * resolution * 1000) / 2.0;
      rgn.hextent.ylon = (lon_extent * resolution * 1000) / 2.0;

    } else {

      MTK_ERR_CODE_JUMP(MTK_BAD_ARGUMENT);

   }

  } else {

    MTK_ERR_CODE_JUMP(MTK_BAD_ARGUMENT);

  }

  *region = rgn;

  return MTK_SUCCESS;

ERROR_HANDLE:
  return status_code;
}