function localFilename(url)	// removing path
{
	var x = url.lastIndexOf("/");
	url = url.slice(x + 1);
	return url;		
}


// images are loaded asynchronously with no delay

function preloading(name)
{
	var xhr=createXHR();   // new instance of object
	xhr.open("GET", name, true); 
	xhr.send(null);  // we don't need for the result, just loading it in memory
} 

function enlarge(element, doss)
{
	var name = element.src;
	var dossier=doss;

	name = localFilename(name);
	

	name = "terrain/"+ dossier+"/moyen/" + name ;  // restore path and add the new "big-" prefix

	// building a string to display the image
	
	var str = "<img src='" + name + "' >";
	document.getElementById("bigview").innerHTML = str;

}