How to transform/convert Coordinate Reference System with Proj4 and php

Question

Basically my question is:

Can I combine the functions of proj4 with php in my server?

For example, I would like to know if it is possible get data in WGS84 and transform in ETRS89.

I need to get WGS84 data with php, then use proj4 to transform them to ETRS89 and finally use them in php.

If the answer is right, how can I configure php and proj4 to work together???

Thanks!!!

Answer 1

Yes you can get them to work together. Below is a sample of code from a php page I coded that uses proj4js, mine is slightly different going from a state plane into wgs84 but the concept is the same. (The syntax is a little off as I had problems pasting it into a code block and my code is sort of spread all over the place in a couple php files but I think you can follow the logic)

enter code here

require_once "config.php";
   foreach ($zones as $id => $zone) {
     $zone_selector .= '<option    value="'.$id.'">'.$zone['name'].'</option>';}
if ($_REQUEST['zone']) {
    $zone_id = $_REQUEST['zone'];
    $zone_name = $zones[$zone_id]['name'];
    $zone_vars = $zones[$zone_id]['vars'];}
if (!$zone_name) $zone_name = "State Plane Coordinates Converter";

points = new Array();
noaa_points = new Array();
var p;
var thispoint;

Proj4js.defs["'.$zone_id.'"] = "'.$zone_vars.'";

var dest = new Proj4js.Proj("EPSG:4326");  /* Lat and Lon projection */
var source = new Proj4js.Proj("'.$zone_id.'");


if ($_REQUEST['n'] && $_REQUEST['e']) 
{echo '
p = new Proj4js.Point('.$_REQUEST['e'].','.$_REQUEST['n'].');
Proj4js.transform(source,dest,p);
points.push({num:1,north:"'.$_REQUEST['n'].'",east:"'.$_REQUEST['e'].'",zone:"'.$zone_name.'",elev:0,desc:"Single Converted Point",lat:p.y,lng:p.x,noaalat:0,noaalng:0});

Answer 2

If you use geoserver you can configure it to do transformations from source. Also WGS84 is practically same as ETRS89 (<1m) (You need to know when it's measured to do more accurate transformations) So you can probably play dump and just assume that they are same.

Have you considered PostGIS -> Geoserver -> PHP app stack? In that configurationyou would have PostGIS and Geoserver which both are capable to transform data.

Something like load data into PostGIS , do st_Transform , use geoserver view to server WFS or WMS layer. Or you could just use PostGIS + (SQL) from PHP, where PostGIS does all hard GIS functions and php only stores/vies data from database.