[Mapserver-users] get proj.4 parameters from a raster image.
pond bear
pond_bear at hotmail.com
Fri Jun 27 13:16:28 EDT 2003
thanks a lot.
I just write a PHP script to get the projection type.
This script requires gdalinfo.
<?php
//change it to your image's path
define('working_path','/image');
@ chdir (working_path) or die("Cannot set the current working
directory<br>.");
//get the projection information from the raster file
//and put it into an array.
function proj_init($file) {
//using gdalinfo to get information of the image and put the information
into $command_output
exec("gdalinfo $file", $command_output, $return_value);
if ($return_value){
die ("The file $file doesn't exist, please check and input it
again.<br>");
}else{
//put projection information in array proj
$proj_arr=array();
for ($i = 0; $i < count($command_output); $i++ ) {
//search proj information in lines containing '['
//echo $command_output[$i].'<br>';
if(strpos($command_output[$i],'[')){
/*remove ']' and ',' at the end of the line
remove ' ' at the beginning of the line
remove double quotes*/
$output_line=ereg_replace('^ *|\"|\]*,?$','',$command_output[$i]);
$output_line_arr=explode('[',$output_line);
$proj_arr[$output_line_arr[0]][]=$output_line_arr[1];
}//end if strpos($command_output[$i],'[')
}
}
for ($i =0;$i< count($proj_arr['PARAMETER']);$i++)
$proj_arr['PARAMETER'][$i]=end(explode(',',$proj_arr['PARAMETER'][$i]));
//print_r($proj_arr);
//echo '<br>';
return $proj_arr;
} //end of function proj_init
function get_type($type) {
if ($type=='Lambert_Azimuthal_Equal_Area')
$proj_type='proj=laea';
elseif ($type=='Albers_Conic_Equal_Area')
$proj_type='proj=aea';
elseif ($type=='Transverse_Mercator')
$proj_type='proj=utm';
else die("The projection of the image isn't supported yet");
return $proj_type;
}
function get_datum($datum) {
if ($datum=='North_American_Datum_1983')
$datum_string='datum=NAD83';
elseif ($datum == 'WGS_1984')
$datum_string='datum=WGS84';
else die('unknow datum');
return $datum_string;
}
function get_ellips($ellips) {
if ($ellips[0]=='Unknown') {
$a=$SPHEROID[1];
$b=$SPHEROID[1]-$SPHEROID[0];
$ellips_string='a='.$a.'+b='.$b;
} elseif ($ellips[0]=='WGS 84') {
$ellips_string='ellips=WGS84';
} elseif ($ellips[0]=='GRS 1980'){
$ellips_string='ellips=GRS80';
} else die('unknown spheroid');
return $ellips_string;
}
/*
proj=laea +lat_0=Latitude at projection center
+lon_0=Longitude at projection center
+x_0=False Easting
+y_0=False Northing
+proj=aea +lat_1=Latitude of first standard parallel
+lat_2=Latitude of second standard parallel
+lat_0=Latitude of false origin
+lon_0=Longitude of false origin
+x_0=Easting of false origin
+y_0=Northing of false origin
*/
function get_parameter($parameter,$type){
$para=array();
if ($type=='proj=laea'){
$para[]='lat_0='.$parameter[0];
$para[]='lon_0='.$parameter[1];
$para[]='x_0='.$parameter[2];
$para[]='y_0='.$parameter[3];
} elseif ($type=='proj=aea'){
$para[]='lat_1='.$parameter[0];
$para[]='lat_2='.$parameter[1];
$para[]='lat_0='.$parameter[2];
$para[]='lon_0='.$parameter[3];
$para[]='x_0='.$parameter[4];
$para[]='y_0='.$parameter[5];
} elseif ($type=='proj=utm'){
$zone_number=(int)((183+$parameter[1])/6);
$para[]='zone='.$zone_number;
} else die('unknow projection');
return $para;
}
function get_proj($img_name) {
$proj=proj_init($img_name);
$projection=array();
$projection[]=get_type($proj['PROJECTION'][0]);
$projection[]=get_datum($proj['DATUM'][0]);
$spheroid=explode(',',$proj['SPHEROID'][0]);
$projection[]=get_ellips($spheroid);
$parameter=get_parameter($proj['PARAMETER'],$projection[0]);
$projection=array_merge($projection,$parameter);
$proj_string=$proj_type.'+'.$proj_datum.'+'.$proj_ellips;
return $projection;
} //end of function get_proj
if (!$_POST['file_name']){
?>
<html>
<head>
<title>Please input the file name </title>
</head>
<body>
<form method=POST action="<?= $PHP_SELF; ?>" >
File name:
<input TYPE=file NAME="file_name" SIZE=30 > <br>
<input TYPE=submit VALUE="Submit">
</body>
</html>
<?php
} else {
$projection=get_proj($_POST['file_name']);
print_r($projection);
}
?>
University of North Dakota
>From: "Juanse" <georef at tie.cl>
>To: "pond bear" <pond_bear at hotmail.com>
>Subject: RE: [Mapserver-users] get proj.4 parameters from a raster image.
>Date: Thu, 26 Jun 2003 10:39:19 -0400
>
>Do not know if Chips can do it because i am starting to use it, but Chips
>is
>an excelent piece of software for handling georeferenced rasters that i
>have
>just found. And it is crackeable and unexpensive if you can buy it, and
>with
>decent 15 days on trial (being able to export/save changes), and then keeps
>on working without saving capabilities.
>
>check here http://www.geogr.ku.dk/chips/
>
>for the crack ... ask.
>
>juanse
>temuko-Chile
>
>
>----- Original Message -----
>From: pond bear <pond_bear at hotmail.com>
>To: <mapserver-users at lists.gis.umn.edu>
>Sent: Thursday, June 26, 2003 3:58 PM
>Subject: [Mapserver-users] get proj.4 parameters from a raster image.
>
>
> > Hi all
> >
> > Is there any tools which can read the raster tif file and return the
>proj.4
> > string of the image.
> >
> > Jing
> > University of North Dakota
> >
> > _________________________________________________________________
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