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I am sure my question has been answered in the past but I would really appreciate it if someone could help me with this... I have downloaded a KML point file from Google earth and I imported it into ArcMap. I cannot figure out what to do in order to project it correctly. My dataset is set to WGS 1984 UTM zone 34N and the KML file is in WGS 1984. The difference of the file's display in ArcMap and Google earth is not that dramatic but some points fall into the sea which is bad for the anaysis I am trying to perform. I tried to project the Google earth point file in WGS 1984 Web Mercator (Auxiliary Sphere), but it still didn't display properly... Can somebody please explain how it works with Google earth and ArcGIS projections? Thank you in advance for any response :)

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Do you have to keep it in KML format? If not, might want to bring into QGIS and convert to SHP with a projection of WGS 84, then bring into ArcGIS as a SHP and assign the correct transformation so the points align better... –  mapBaker Jul 2 '13 at 17:12
    
THank you for your response, I converted the KML file in ArcCatalog into a layer (Analysis Tools/Conversion Tools/KML to layer)... Moreover I do not have QGIS... –  Anna Xilakis Jul 2 '13 at 18:05
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Could the UTM data actually be on a different GeoCRS/datum like GGRS87? Beyond the points that are offshore, does it look like there's an offset to all of the points? If so, that could point to a different datum. –  mkennedy Jul 2 '13 at 19:18
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For UTM Zone 34N, there are also datum definitions ED50, ELD79, LGD2006, WGS72 and WGS72BE. I would suggest to try one of those for your dataset, and leave the KML file to WGS84. If you can provide sample coordinates in both datasets, we could try to figure out the correct CRS. Can you measure the offset in metres? –  Andre Joost Jul 3 '13 at 15:37
    
@mkennedy thank you for your response. You are right, it seems that all the points are slightly displaced. I checked all the possible appropriate datum/projection combinations but I cannot align it perfectly, or at least so that all the points fall onto land.The fact that in Google earth the points are in the correct place means that there is definitely something I am doing wrong... –  Anna Xilakis Jul 4 '13 at 7:58

3 Answers 3

up vote 2 down vote accepted

I have downloaded the ASTER data you mentioned, and got an offset of around 120m.

I'm afraid that's all the ASTER database is able to offer. They promise an offset of 20m at 95% of the world, but you can not rely on that.

The data is in WGS84, same as Google Earth. So it is not a matter of datum shifts at all.

If you want a more precise shoreline, you can take that of Openstreetmap, linked and described here: http://wiki.openstreetmap.org/wiki/Coastline#Rendering

The processed_p shapefile is much closer to the aerial imagery than the aster data.

If you want height contour lines, you might use ASTER anyhow.

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Thank you so much!! I was really frustrated cause I couldn't figure out what I was doing wrong... You totally solved my problem :) –  Anna Xilakis Jul 4 '13 at 19:04

Apply below transformation method to project your data in ArcMap.

1)Open New Arcmap.

2)Add your Imagery files which you downloaded from Google earth.

3)Add your existing geodatabase layer files into arcmap (Ex:Layers or shapes)

4)Right click in the Arcmap window and select Dataframe Properties.

enter image description here

5) A New window will open and then select your Layer file (Google/Imagery file) and then click Transformations Now you need to choose correct datum in Convert from: location and then Into: location and you need to choose your datum(Co-ordinate system) in this case my Datum is Asia\Qatar 1974 and choose appropriate using: method and click Ok. and APPly. enter image description here

6) Now check your map if it's aligned properly or not, if not and then come back to the same location open Dataframe properties this time you need select Projected Coordinate System and select National Grids choose your national grid and hit Apply Now your data should be aligned properly. enter image description here

Hope this helpful.

best of luck..

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thank you for your response! –  Anna Xilakis Jul 4 '13 at 10:36

The Easiest way to do this before you add the data or imagery is :

1) Open Arcmap 2) right click the Layer properties 3) Hit the Coordinate System tab. 4) if you have the 10.0 or later: Type the name of the coordinate system ie:(WGS 1984 Web Mercator (Auxiliary Sphere)). 5) Select it. 6) Bring in the data 7) right click on the data and select Data to Export Data 8) On the Export Data dialog box : Choose "the data frame" ( Make sure you select it right) 9) Review the the data source to ensure it is correct coordinate system or you can test it by clear out the "Clear Search"

Good luck

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Thank you @PROBERT , I tried it but it won't work.. I have the impression that my DEM retrieved from ASTER has a problem with the coastline and lacks detail? –  Anna Xilakis Jul 4 '13 at 13:02
    
Are you saying that the ASTER wasn't smooth as they should be ? like artifacts etc ? –  PROBERT Jul 4 '13 at 20:40

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