[mapserver-users] Problems with MapScript and setProjection

Tue Feb 10 12:20:44 EST 2009

Pietro, that was exactly what I needed. Thanks.

The example below pulls everything together and works under MapServer 
5.2.1 (tested under Fedora 10). If someone hits this in the mailing list 
archive later and is trying to figure out reprojection, start at the end 
with the comment "reproject (if needed) and draw".

If someone who already has a wiki login, wants to add it to the page 
that Tom Kralidis set up, feel free.

Tim Wood

<?PHP

/**
 * Code to create a map from a shapefile
 * and then (optionally) reproject the whole thing
 *
 * If you just want to look at the reprojection stuff, start
 * with the "reproject (if needed) and draw" section at the end.
 * The rest
 *
 * Created by Tim Wood from code and input
 * by Tom Kralidis [Ontario], Pietro Gianninni and Stephen Jones.
 *
 * No copyright restrictions
 */

// ---------------------------
// Configuration
// aka set a bunch of variables and load the mapscript extension
//

// Where my key directories are located
$doc_root = '/var/www/html';
$rel_path = "example1/round2";

$base_path = "$doc_root/$rel_path";

// An empty map file
$base_map = "$base_path/data/empty.map";   // just the words MAP and END 
on dif. lines... really

// The data I'm using
$shape_path    = "$base_path/data/zcta/zt08_d00_shp/";    // a goofy 
path I'm too lazy to fix
$shape_file = "gfsa000b06a_e";                            // works with 
or w/o the extension
$shape_file_projection = "+proj=longlat +datum=NAD83";

// The Extents (area) I want in latitude, longitude
list( $ex0, $ex1, $ex2, $ex3 ) = array(-140, 40, -50, 55 );

// Describe the rest of my output
$output_projection = '';
$output_projection = "+proj=tcc +lon_0=90w +ellps=GRS80";
$output_file_rel = "output/index2.png";
$output_file_path = "$base_path/$output_file_rel";
list($output_width, $output_height ) = array( 600, 500 );

// Load MapScript extension
if (!extension_loaded("MapScript"))  dl('php_mapscript.'.PHP_SHLIB_SUFFIX);

// ---------------------------
// Function(s)
//

/**
 * Reproject a $map from $shape_file_projection to $output_projection
 */
function reproject_map( &$map, $shape_file_projection, 
$output_projection ) {
    $origProjObj = ms_newProjectionObj( $shape_file_projection );
    $newProjObj = ms_newProjectionObj( $output_projection );

    $oRect = $map->extent;
    $oRect->project( $origProjObj, $newProjObj );
    $map->setExtent( $oRect->minx, $oRect->miny, $oRect->maxx, 
$oRect->maxy );
    $map->setProjection( $output_projection  );
}

// ---------------------------
// The Main Code
//

// add map
$map = ms_newMapObj( $base_map );
$map->set( 'name', 'my_map' );    // If we're using a blank map file, 
give it a name

// Set the extent
$map->setExtent( $ex0, $ex1, $ex2, $ex3 );

// Set the shapepath
$map->set( 'shapepath', $shape_path );
// Set the output format and size
$map->selectOutputFormat( 'png' );
$map->setSize( $output_width, $output_height );

// add new layer to map
$layer = ms_newLayerObj($map);
$layer->set("name", "foo");
$layer->set("status", MS_ON);
$layer->set("data", $shape_file );
$layer->set("type", MS_SHAPE_POLYGON );
$layer->setProjection( $shape_file_projection );
$layer->set("template", "ttt");    // hide errors that appear iff 
$output_projection is set?
$layer->set("dump", "true");

// add new class to new layer
$class = ms_newClassObj($layer);
$class->set("name", "foo");

// add new style to new class
$style = ms_newStyleObj($class);
$style->color->setRGB(255, 0, 0);
$style->outlinecolor->setRGB( 128,128,128 );

// reproject (if needed) and draw
if( $output_projection != '' ) {
    reproject_map( $map, $shape_file_projection, $output_projection );
    $image = $map->drawQuery();
} else {
    // draw
    $image = $map->draw();
}

// ---------------------------
// Output the image
//

$image->saveImage( $output_file_path );

?>
<html>
<body>
    <img src="<?PHP print $output_file_rel; ?>">
</body>
</html>
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