ASC raster in wrong place, but the spatial reference is correct.

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05-19-2021 01:36 PM
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dagiannitto
New Contributor II

Hi, I have a weird problem with some lidar data i downloaded. I added it to my map as a .asc raster file, but it has appeared in Africa when it should be in Scotland. The spatial reference is correct, so i don't know why it is in the wrong place?

Thanks.

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JayantaPoddar
MVP Esteemed Contributor

Thank you for the additional info. 

The correct coordinate system could be British_National_Grid.

Could you use Define Projection, for defining British_National_Grid as the coordinate system?



Think Location

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JayantaPoddar
MVP Esteemed Contributor

What is the spatial reference used? What is the extent of the layer (check Layer Properties > Source)? Share its screenshot, if possible.

I believe the raster could have been wrongly defined a Projected Coordinate System whereas the values are referring to that of a Geographic Coordinate System (Decimal Degrees).

Could you check if using Define Projection to the Raster dataset (Coordinate System: GCS_WGS_1984) resolves the issue.



Think Location
dagiannitto
New Contributor II

Hi Jayanta, I have already ensured that the projected coordinates system is WGS 1984, and the UTM zone is also correct. I will be able to send a screenshot shortly

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dagiannitto
New Contributor II

dagiannitto_0-1621501471198.pngdagiannitto_1-1621501478974.pngdagiannitto_2-1621501483895.png

 

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JayantaPoddar
MVP Esteemed Contributor

 

That extent tells me that the data is not georeferenced. Lidar could be just the raw data, with no spatial reference. Please check if the Lidar data is  overlaying properly on map? 

Could you tell me from where you downloaded the data? If it's open for public, please share the URL.

Edit: My mistake. I assumed the comma to be a period in the XY extent values.



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dagiannitto
New Contributor II

Ah ok. I downloaded the data from Edina Digimap Lidar Data Download (edina.ac.uk) I don't believe it is open for the public as you need an account to access the data. 

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JayantaPoddar
MVP Esteemed Contributor

Thank you for the additional info. 

The correct coordinate system could be British_National_Grid.

Could you use Define Projection, for defining British_National_Grid as the coordinate system?



Think Location
dagiannitto
New Contributor II

I am trying to now, do you know if it would be projected or geographic coordinate system?

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dagiannitto
New Contributor II

Actually i have got it, and it is all sorted now. thank you so much!

 

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scarson_sbbg
New Contributor

@dagiannitto What did you do to fix your issue?

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