Q0004: I have exported a TIF map image, when I import the image to a GIS product it is placed in the wrong location!

A: You have selected the wrong projection, coordinate system, datum or distance units in the GIS application.

Here is how you can troubleshoot this problem.

1. Write a GeoTIF image. Your GIS application should automatically figure out the exported map's projection, datum and scale factor.

2. Instead of exporting a huge map, export a small map (2 miles x 2 miles) with both a UTM and Lat/Lon grid imposed. 

1. Import the smaller map into your GIS application
2. zoom extents so you can see the imported map
3. zoom into the All Topo generated base map until you can see the base maps and a grid intersection:

Now place the mouse cursor over a grid intersection (as shown above) and compare the coordinate displayed by the GIS application (650,005.5 4,531,001.7 above) with the grid coordinate (650,000 4,531,000) shown by the exported map.

Some common errors:

• If you are off a couple of hundred feet to the west, then you most likely have the incorrect datum set in the GIS application.
• If you are 6 degrees of longitude off, then you most likely have the wrong UTM Zone number.
• If you are way, way north and way, way east then you most likely have exported the map with distance and scale units of METERS and the GIS application is using FEET.
• If you are using State Plane coordinates: you may have the wrong ZONE or the wrong distance units (feet or meters).

If you are absolutely positive you have done everything correctly then give us a call. We will ask you to make a test map 2 miles square, with UTM and Lat/Lon grids and email it to us. We will need the coordinate that your GIS application reports for the bottom-left-most grid intersection of the map you build. We will check the registration in several other GIS and mapping products and report the results. We rarely find All Topo produced maps that incorrectly georeferenced (remember there are thousands of people using All Topo Maps, building thousands of BigTopos everyday.)

K: mis-registration, coordinates off, exported map, wrong datum, wrong scale factor.

02/12/2004 16:36