Coordinates to Pixels based on Zoom

The (very) short answer is: Have a look at at the wiki and the question that was asked earlier.

As this does not resolve the submitters question, I'll edit my answer and expand it. For the original example URL we can extract the following parameters: longitude 89.08805 west, latitude 30.6393 north and zoomlevel 6.5156731549786215. (Note that this is a non integer zoomlevel and might break lots of code that only expects integer zoomlevels.) However looking at the output resulting gif it looks like the website truncates the zoomlevel and really uses zoomlevel 6.

Using this really simple java code which would support fractional zoomlevels if needed in the future we can convert lat and long to tile coordinates.

double lon = -89.08805;
double lat = 30.6393;
double zoom = 6; // 6.5156731549786215 would be possible too

double lon_rad = Math.toRadians(lon);
double lat_rad = Math.toRadians(lat);
double n = Math.pow(2.0, zoom);

double tileX = ((lon + 180) / 360) * n;
double tileY = (1 - (Math.log(Math.tan(lat_rad) + 1.0/Math.cos(lat_rad)) / Math.PI)) * n / 2.0;

System.out.println("tileX = "+tileX+" tileY = "+tileY);

It computes the location of the map center in tile coordinates as:

tileX = 16.162124444444444
tileY = 26.273150713795616

For Forth Worth I'll use longitude 97.3327459 east and latitude 32.753177 north which translates into:

tileX = 14.696400728888888
tileY = 25.831427880285347

So Fort Worth is 1.465723715555556 tiles left and 0.441722833510269 tiles above the map center. To get to pixels all you would have to do is to multiply by 256 pixels per tile. Thus we get the information that Fort Worth is 375 pixels left and 113 pixels above the map center.

Given that the map is 1000 pixels wide and 700 pixels wide this means that Fort Worth is 125 pixels from the left boundary and 237 pixels down from the top.

hey, i wanted to ask how do you calculate that for Fort Worth is 1.465723715555556 tiles left and 0.441722833510269 tiles above the map center when you have tileX and tileY, what kind of calculations follow

hey plz how did you found that : Fort Worth is 125 pixels from the left boundary and 237 pixels down from the top.

I know this is old. But just as vaddinDev, I struggle to understand the conversion to the 100x700 map pixel location. What I think is used for calculation is that the tile is 256 images wide and tall.

So,

for width: 375 x 3 = 1125 => 1125-1000 = 125 pixels from left of image)

for height: 113 x 4 = 452 => 452-700 = -247 pixels down from top of image (I think the 237 in the original answer is a typo).

PLEASE correct me if I am stretching the math here!!!