1

I was asked to created a point shapefile of a cemetery. The points display correctly in QGIS but not in ArcGIS. I think the issue is with the coordinate system I created it in (WGS 84 / UTM zone 17N).

screenshot

I've linked the file below for you to try:

https://www.dropbox.com/sh/lv7dc43elfc031r/AADtbioR1wGzmTLikMCKnqOwa?dl=0

What mistake am I making? There is something I am doing wrong during the creation of the shapefile in QGIS.

Edit1: I originally gathered the data using a Garmin GPS unit tagging a sample size of spots. I uploaded the file onto QGIS and created the polyline and polygon shapefiles you can see in the example. These display fine in ArcGIS Desktop. First, let me be clear that I am new to GIS and even newer to QGIS (I completely self learned the application). I created the point file from scratch by referring to the satellite image plugin of Google and Bing Maps. I also referred to a paper "map" of the cemetery from the 1950's that I won't upload for privacy reasons. My client just wants a digital map to reference and print when needed. They are not GIS professionals but clerks who want to be able to quickly go onto ArcGIS, see if the plot is free or not. Back on topic.

Looking back while I was creating the points, I believe I did something that mkennedy is referring to - changed the geographic coordinate reference. Big rookie mistake on my part.

The thing is, I'm confused and frustrated. Very frustrated. I don't have access to ArcGIS at the moment and cannot play around.

  • 5
    What issue are you seeing in ArcGIS. You need to provide more information, so the community knows what to look for. – Ryan Garnett Feb 12 '15 at 3:45
  • 2
    How do you know they're correct or incorrect? Are you comparing the points against orthophotography/imagery. What is the coordinate system of the map in ArcGis? Some spatial references need a transformation (between datums) to display correctly in ArcGis. Can you provide a screen shot of the same area in ArcGis? – Michael Stimson Feb 12 '15 at 4:20
  • Michael, I currently do not have access to ArcGIS despite but Simbamangu's description about the difference in X extents is accurate. – Andrew Feb 13 '15 at 23:26
1

I think what happened is that the original data is in lat/lon. Somehow it was assigned the UTM coordinate reference system, and unprojected to WGS 1984, a geographic coordinate reference system. Having "Y" or latitude values near zero that should be at mid-latitudes is a classic sign of a mistaken UTM definition for latitude/longitude data.

I don't know QGIS. One workflow in ArcGIS to recover the data is to project the WGS84 shapefile to UTM 17N (WKID: 32617). Then redefine it using the Define Projection Tool or the data's property page in ArcCatalog to WGS 1984.

Perhaps someone else can speak to what might have happened in QGIS. Feel free to incorporate my answer into yours if you want to.

  • Thanks, kennedy. Although I'm still confused. Can you please explain like I'm 5. Can I save/recover the file entirely in ArcGIS? – Andrew Feb 13 '15 at 23:42
  • I think so. The steps are in the 2nd paragraph. Use the Project Tool to go to 32617, WGS 1984 UTM 17 North. Then use the Define Projection Tool to change the CRS to WGS 1984 (geographic CRS). I think that will recover the original data. – mkennedy Feb 14 '15 at 0:03
  • Thanks, mkennedy! This solved my issue. Thank you for explaining out the steps again. – Andrew Feb 18 '15 at 23:40
2

There is definitely something wrong with your shapefile - viewing it in QGIS, the extents are:

-85.489443389,0.000406358 : -85.489443375,0.000406369

... placing it somewhere off the coast of Equador.

Another clue: the difference in X extents (-85.489443389 - -85.489443375) is 0.000000014 decimal degrees - which makes the whole cemetary something around 150 microns wide!

You may have transformed 'normal' UTM coordinates such as 406358 8548944 into decimal degrees (-85.489443389,0.000406358), dividing each by a factor and then applying the WGS84 geographic CRS to the file.

You didn't mention how you created the file, but presumably have a table of eastings (i.e. 406358) and northings (8548944). You should add the table (csv file?) as a 'delimited text' file in QGIS, identifying the eastings as X and the northings as Y from the correct columns, and assign the layer with the correct CRS (32618). See here for more on QGIS and delimited text.

  • Please note that the image shows the longitudes as approximately -79, not -85 and the latitudes as approximately 45. Those differences are from unprojecting the coordinates from an incorrect CRS, not by scaling them. – mkennedy Feb 12 '15 at 18:52
  • The lat/lon bounds I mention here was from downloading the file and viewing it by itself - but seems like you were on the right track in the end! I should probably delete this answer. – Simbamangu Feb 22 '15 at 15:30

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

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