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This question already has an answer here:

I'm using ArcMap 10.3 on Windows 10.

I have a number of .bil and .tif files pertaining to altitude and weather data. I want to open these in ArcMap. When I attempt to add them to the map I get this dialogue box: Box

Can someone walk me through how to use this to open these files in ArcMap?

This is the error that I've encountered trying to do this myself: Box1

Or it throws up a generic "can't open this" error. I would share a screenshot of this but I can't replicate the error.

The goal is to use these data to find the average temperature, slope, etc for a number of points (n=157), so I assume I would need the .bil/.tif to have a spatial referencing system. I'm using the Irish Grid coordinate system.

EDIT I used the Define Projection tool on the files and they did change to Irish Grid (when I right click the feature class go to Properties < Source it does say it's in Irish Grid) - but the data doesn't line up with all my shapefiles in the Irish grid, it's "off in space" just the same as having no coordinate system. I tried this with both file types and the result is the same.

marked as duplicate by PolyGeo arcgis-desktop Aug 19 '16 at 6:57

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

  • What happens when you click Yes and OK to the two dialog boxes? – Midavalo Aug 9 '16 at 19:16
  • unknown spatial reference is not an error - you need to assign a projection to your images (tif will be tfw) webhelp.esri.com/arcgisdesktop/9.3/… – Mapperz Aug 9 '16 at 19:17
  • @Midavalo: The same dialogue box appears when I click Yes. The image does appear if I "zoom to" but can't be projected. Are these files meant to have an attribute table? I can't open it when I click Yes and Ok to the boxes. – rakuenvi Aug 9 '16 at 19:19
  • @Mapperz: I can't assign one, which is the issue. If I go to ArcToolbox > Project the file does not appear as an input feature and cannot be projected. – rakuenvi Aug 9 '16 at 19:20
  • If you don't have spatial reference information (possibly should be a .tfw and .blw files with your images) you will need to georeference the images yourself. – Midavalo Aug 9 '16 at 19:28
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Building pyramids will not alter your data in any way, it only speeds up the display of the data as you pan & zoom.

Use the Define Projection tool to indicate what is the current projection/coordinate system of the rasters. The Project tool is for creating a new dataset in a different projection. The source of your raster data should know what projection should be used.

You may need to define the projection before pyramids can be built.

  • Thanks. As per your answer, I used the define projection tool and it has changed to Irish Grid (when I right click the feature class go to Properties < Source it does say it's in Irish Grid) - but the data doesn't line up with all my shapefiles in the Irish grid, it's "off in space" just the same as having no coordinate system. I tried this with both file types and the result is the same. – rakuenvi Aug 9 '16 at 19:41
  • What I often do with undefined data is add it to an ArcMap project with projected data of known quality, then experiment by setting the Data Frame coordinate system to those commonly used in the region. When your unknown data suddenly lines up, that's probably the coordinate system it is in. – Bjorn Aug 9 '16 at 19:48
  • I'm afraid I don't understand - I've added the undefined data to my current project that contains other data in Irish grid like counties, roads, etc all from the Environmental Protection Agency website (so "known quality"), but it doesn't line up. Does that mean I need to change the coordinate system of all my other data to match whatever one my undefined data works best with? That would ruin weeks of work, as I would need to run my analyses again for the new coordinate system... – rakuenvi Aug 9 '16 at 20:02
  • No, do not change the coordinate system of any good data! Go into the properties of the data frame, select the Coordinate Systems tab, and change the settings there. If you happen to choose the one that your undefined data uses, it will then line up with your defined data. – Bjorn Aug 9 '16 at 20:12
  • Oh ok. That will be extremely tedious as the data could be in any of the coordinate systems as it's from a worldwide dataset (WorldClim)... I might just try looking for another place to get weather and topography data from that has a coordinate system defined. – rakuenvi Aug 9 '16 at 20:23

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