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MGRS conversion fixes #68

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201 changes: 84 additions & 117 deletions src/gov/nasa/worldwind/geom/coords/MGRSCoordConverter.java
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Original file line number Diff line number Diff line change
Expand Up @@ -37,7 +37,7 @@ class MGRSCoordConverter
private static final int MGRS_ZONE_ERROR = 0x0100;
private static final int MGRS_HEMISPHERE_ERROR = 0x0200;
private static final int MGRS_LAT_WARNING = 0x0400;
private static final int MGRS_NOZONE_WARNING = 0x0800;
// private static final int MGRS_NOZONE_WARNING = 0x0800;
private static final int MGRS_UTM_ERROR = 0x1000;
private static final int MGRS_UPS_ERROR = 0x2000;

Expand All @@ -62,7 +62,7 @@ class MGRSCoordConverter
// Ellipsoid parameters, default to WGS 84
private double MGRS_a = 6378137.0; // Semi-major axis of ellipsoid in meters
private double MGRS_f = 1 / 298.257223563; // Flattening of ellipsoid
private double MGRS_recpf = 298.257223563;
// private double MGRS_recpf = 298.257223563;
private String MGRS_Ellipsoid_Code = "WE";

private Globe globe;
Expand Down Expand Up @@ -255,9 +255,11 @@ public long convertMGRSToGeodetic(String MGRSString)
{
latitude = 0;
longitude = 0;
long error_code = checkZone(MGRSString);
if (error_code == MGRS_NO_ERROR)
{
MGRSComponents mgrs = breakMGRSString(MGRSString);
if (mgrs == null) return last_error;

long error_code = MGRS_NO_ERROR;
if (mgrs.zone != 0) {
UTMCoord UTM = convertMGRSToUTM(MGRSString);
if (UTM != null)
{
Expand All @@ -267,9 +269,8 @@ public long convertMGRSToGeodetic(String MGRSString)
else
error_code = MGRS_UTM_ERROR;
}
else if (error_code == MGRS_NOZONE_WARNING)
else
{
// TODO: polar conversion
UPSCoord UPS = convertMGRSToUPS(MGRSString);
if (UPS != null)
{
Expand Down Expand Up @@ -314,17 +315,15 @@ private MGRSComponents breakMGRSString(String MGRSString)
long northing = 0;
int precision = 0;

while (i < MGRSString.length() && MGRSString.charAt(i) == ' ')
{
i++; /* skip any leading blanks */
}
MGRSString = MGRSString.toUpperCase().replaceAll("\\s", "");
j = i;
while (i < MGRSString.length() && Character.isDigit(MGRSString.charAt(i)))
while (i < MGRSString.length() && Character.isDigit(' '))
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@gbburkhardt, I'm not sure this change is correct. The Character.isDigit(' ') call will always return false.

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I think we can drop this while loop from the look of it.

{
i++;
}
num_digits = i - j;
if (num_digits <= 2)
{
if (num_digits > 0)
{
/* get zone */
Expand All @@ -333,7 +332,11 @@ private MGRSComponents breakMGRSString(String MGRSString)
error_code |= MGRS_STRING_ERROR;
}
else
error_code |= MGRS_STRING_ERROR;
{
zone = 0;
}
}

j = i;

while (i < MGRSString.length() && Character.isLetter(MGRSString.charAt(i)))
Expand Down Expand Up @@ -394,40 +397,6 @@ private MGRSComponents breakMGRSString(String MGRSString)
return null;
}

/**
* The function Check_Zone receives an MGRS coordinate string. If a zone is given, MGRS_NO_ERROR is returned.
* Otherwise, MGRS_NOZONE_WARNING. is returned.
*
* @param MGRSString the MGRS coordinate string.
*
* @return the error code.
*/
private long checkZone(String MGRSString)
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@gbburkhardt, is it ok for us to drop this checkZone() method? I see that it was used in the convertMGRSToGeodetic() method for error-checking. I suppose the breakMGRSString() method provides similar error-checking.

{
int i = 0;
int j = 0;
int num_digits = 0;
long error_code = MGRS_NO_ERROR;

/* skip any leading blanks */
while (i < MGRSString.length() && MGRSString.charAt(i) == ' ')
{
i++;
}
j = i;
while (i < MGRSString.length() && Character.isDigit(MGRSString.charAt(i)))
{
i++;
}
num_digits = i - j;
if (num_digits > 2)
error_code |= MGRS_STRING_ERROR;
else if (num_digits <= 0)
error_code |= MGRS_NOZONE_WARNING;

return error_code;
}

/**
* The function Get_Latitude_Band_Min_Northing receives a latitude band letter and uses the Latitude_Band_Table to
* determine the minimum northing for that latitude band letter. Updates min_northing.
Expand Down Expand Up @@ -503,13 +472,9 @@ else if ((letter >= LETTER_P) && (letter <= LETTER_X))
*/
private UTMCoord convertMGRSToUTM(String MGRSString)
{
double scaled_min_northing;
double grid_easting; /* Easting for 100,000 meter grid square */
double grid_northing; /* Northing for 100,000 meter grid square */
double temp_grid_northing = 0.0;
double fabs_grid_northing = 0.0;
double latitude = 0.0;
double longitude = 0.0;
double divisor = 1.0;
long error_code = MGRS_NO_ERROR;

Expand Down Expand Up @@ -622,10 +587,6 @@ private UTMCoord convertMGRSToUTM(String MGRSString)
*/
public long convertGeodeticToMGRS(double latitude, double longitude, int precision)
{
String Hemisphere = AVKey.NORTH;
double Easting = 0.0;
double Northing = 0.0;

MGRSString = "";

long error_code = MGRS_NO_ERROR;
Expand Down Expand Up @@ -861,7 +822,7 @@ private long convertUTMToMGRS(long Zone, double Latitude, double Easting, double
* The function Get_Grid_Values sets the letter range used for the 2nd letter in the MGRS coordinate string, based
* on the set number of the utm zone. It also sets the false northing using a value of A for the second letter of
* the grid square, based on the grid pattern and set number of the utm zone.
* <p>
* <p></p>
* Key values that are set in this function include: ltr2_low_value, ltr2_high_value, and false_northing.
*
* @param zone Zone number
Expand Down Expand Up @@ -1077,84 +1038,90 @@ private UPSCoord convertMGRSToUPS(String MGRS)

MGRSComponents mgrs = breakMGRSString(MGRS);
if (mgrs == null)
{
error_code = this.last_error;

if (mgrs != null && mgrs.zone > 0)
error_code |= MGRS_STRING_ERROR;

if (error_code == MGRS_NO_ERROR)
}
else
{
easting = mgrs.easting;
northing = mgrs.northing;

if (mgrs.latitudeBand >= LETTER_Y)
{
hemisphere = AVKey.NORTH;

index = mgrs.latitudeBand - 22;
ltr2_low_value = upsConstants[index][1]; //.ltr2_low_value;
ltr2_high_value = upsConstants[index][2]; //.ltr2_high_value;
ltr3_high_value = upsConstants[index][3]; //.ltr3_high_value;
false_easting = upsConstants[index][4]; //.false_easting;
false_northing = upsConstants[index][5]; //.false_northing;
}
else
if (mgrs.zone > 0)
{
hemisphere = AVKey.SOUTH;

ltr2_low_value = upsConstants[mgrs.latitudeBand][12]; //.ltr2_low_value;
ltr2_high_value = upsConstants[mgrs.latitudeBand][2]; //.ltr2_high_value;
ltr3_high_value = upsConstants[mgrs.latitudeBand][3]; //.ltr3_high_value;
false_easting = upsConstants[mgrs.latitudeBand][4]; //.false_easting;
false_northing = upsConstants[mgrs.latitudeBand][5]; //.false_northing;
error_code |= MGRS_STRING_ERROR;
}

// Check that the second letter of the MGRS string is within
// the range of valid second letter values
// Also check that the third letter is valid
if ((mgrs.squareLetter1 < ltr2_low_value) || (mgrs.squareLetter1 > ltr2_high_value) ||
((mgrs.squareLetter1 == LETTER_D) || (mgrs.squareLetter1 == LETTER_E) ||
(mgrs.squareLetter1 == LETTER_M) || (mgrs.squareLetter1 == LETTER_N) ||
(mgrs.squareLetter1 == LETTER_V) || (mgrs.squareLetter1 == LETTER_W)) ||
(mgrs.squareLetter2 > ltr3_high_value))
error_code = MGRS_STRING_ERROR;

if (error_code == MGRS_NO_ERROR)
{
grid_northing = (double) mgrs.squareLetter2 * ONEHT + false_northing;
if (mgrs.squareLetter2 > LETTER_I)
grid_northing = grid_northing - ONEHT;
easting = mgrs.easting;
northing = mgrs.northing;

if (mgrs.squareLetter2 > LETTER_O)
grid_northing = grid_northing - ONEHT;

grid_easting = (double) ((mgrs.squareLetter1) - ltr2_low_value) * ONEHT + false_easting;
if (ltr2_low_value != LETTER_A)
if (mgrs.latitudeBand >= LETTER_Y)
{
if (mgrs.squareLetter1 > LETTER_L)
grid_easting = grid_easting - 300000.0;

if (mgrs.squareLetter1 > LETTER_U)
grid_easting = grid_easting - 200000.0;
hemisphere = AVKey.NORTH;

index = mgrs.latitudeBand - 22;
ltr2_low_value = upsConstants[index][1]; //.ltr2_low_value;
ltr2_high_value = upsConstants[index][2]; //.ltr2_high_value;
ltr3_high_value = upsConstants[index][3]; //.ltr3_high_value;
false_easting = upsConstants[index][4]; //.false_easting;
false_northing = upsConstants[index][5]; //.false_northing;
}
else
{
if (mgrs.squareLetter1 > LETTER_C)
grid_easting = grid_easting - 200000.0;

if (mgrs.squareLetter1 > LETTER_I)
grid_easting = grid_easting - ONEHT;
hemisphere = AVKey.SOUTH;

if (mgrs.squareLetter1 > LETTER_L)
grid_easting = grid_easting - 300000.0;
ltr2_low_value = upsConstants[mgrs.latitudeBand][1]; //.ltr2_low_value;
ltr2_high_value = upsConstants[mgrs.latitudeBand][2]; //.ltr2_high_value;
ltr3_high_value = upsConstants[mgrs.latitudeBand][3]; //.ltr3_high_value;
false_easting = upsConstants[mgrs.latitudeBand][4]; //.false_easting;
false_northing = upsConstants[mgrs.latitudeBand][5]; //.false_northing;
}

easting = grid_easting + easting;
northing = grid_northing + northing;
return UPSCoord.fromUPS(hemisphere, easting, northing, globe);
// Check that the second letter of the MGRS string is within
// the range of valid second letter values
// Also check that the third letter is valid
if ((mgrs.squareLetter1 < ltr2_low_value) || (mgrs.squareLetter1 > ltr2_high_value) ||
((mgrs.squareLetter1 == LETTER_D) || (mgrs.squareLetter1 == LETTER_E) ||
(mgrs.squareLetter1 == LETTER_M) || (mgrs.squareLetter1 == LETTER_N) ||
(mgrs.squareLetter1 == LETTER_V) || (mgrs.squareLetter1 == LETTER_W)) ||
(mgrs.squareLetter2 > ltr3_high_value))
error_code = MGRS_STRING_ERROR;

if (error_code == MGRS_NO_ERROR)
{
grid_northing = (double) mgrs.squareLetter2 * ONEHT + false_northing;
if (mgrs.squareLetter2 > LETTER_I)
grid_northing = grid_northing - ONEHT;

if (mgrs.squareLetter2 > LETTER_O)
grid_northing = grid_northing - ONEHT;

grid_easting = (double) ((mgrs.squareLetter1) - ltr2_low_value) * ONEHT + false_easting;
if (ltr2_low_value != LETTER_A)
{
if (mgrs.squareLetter1 > LETTER_L)
grid_easting = grid_easting - 300000.0;

if (mgrs.squareLetter1 > LETTER_U)
grid_easting = grid_easting - 200000.0;
}
else
{
if (mgrs.squareLetter1 > LETTER_C)
grid_easting = grid_easting - 200000.0;

if (mgrs.squareLetter1 > LETTER_I)
grid_easting = grid_easting - ONEHT;

if (mgrs.squareLetter1 > LETTER_L)
grid_easting = grid_easting - 300000.0;
}

easting = grid_easting + easting;
northing = grid_northing + northing;
return UPSCoord.fromUPS(hemisphere, easting, northing, globe);
}
}
}

return null;
}
}
}