I have a copy of some ArcGIS log files with bounding box extent information. This example point should map to Montana.


I know that the format is xMin, yMin, xMax, yMax for the points. I've taken the points to make a center point.

xCenter = (xMax + xMin)/2.0
yCenter = (yMax + yMin)/2.0

It seems like these points are in meters and I'm having difficulty finding a formula to translate them into lat long point pairs. Is there a direct formula I can use in my scirpt for processing? I don't have a copy of arcpy to use which seems to be the most suggested way to solve the problem.

  • Try using the proj4js library which is free to download. This answer provides some of the basics to get started. gis.stackexchange.com/questions/5265/… The hardest part is just making sure you use the correct coordinate system or projections.
    – Eok
    Jul 31, 2015 at 16:46
  • 1
    If the points are near Flathead Lake, EPSG:3857 would be my closest bet for the CRS.
    – AndreJ
    Jul 31, 2015 at 17:21
  • I think you're right that the CRS is EPSG:3857. Jul 31, 2015 at 17:59

2 Answers 2


I found some help from this gis post: How to convert projected coordinates to lat/lon using Python?

and made a python function to solve my problem

def convertEPSGtoWGS(pointX, pointY):
    # Spatial Reference System
    inputEPSG = 3857
    outputEPSG = 4326

    # create a geometry from coordinates
    point = ogr.Geometry(ogr.wkbPoint)
    point.AddPoint(pointX, pointY)

    # create coordinate transformation
    inSpatialRef = osr.SpatialReference()

    outSpatialRef = osr.SpatialReference()

    coordTransform = osr.CoordinateTransformation(inSpatialRef, outSpatialRef)

    # transform point

    # print point in EPSG 4326
    print point.GetX(), point.GetY()

I use 3 ways to convert esri extent bbox to lat long

  1. use esri javascipt api module ( client side projection, fast, no need ajax, no need internet, projection done in your browser, extremely fast)

    first include css, js

link(rel='stylesheet',href='https://js.arcgis.com/4.17/esri/themes/light/main.css') script(src='https://js.arcgis.com/4.17/')

This is my working example: enter image description here

  1. proj4js ( need ajax, internet to read projection string from website, due to website does not allow jsonp, not allow cors, you have to setup your own proxy to bypass CORS problem, not easy for normal user )

But if you already known from what to what, then you can just copy past projection string, no internet needed, all projectin done in your browser.

If you don't know project from what to what, projection wkid is dynamic generated in the runtime, then like I said previously, you must need ajax, need internet to read projection string from website on the fly, in the run time. It is not easy, because you have to bypass CORS problem.

Here is my working example: enter image description here

  1. use Arcgis.com hosted web service ( need internet, very slow, not reliable, if ESRI server is crowded, you might get it very slow. Every ajax request can only conver one pair of lat lng) enter image description here

enter image description here

Here is how to project on website enter image description here

you can get xmin, ymin from here enter image description here

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct.

Not the answer you're looking for? Browse other questions tagged or ask your own question.