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coordinates, projections and data frame

Question asked by FRANESCARUSSO22 on Oct 14, 2016

Hi all,

 

I am writing to ask some help/clarifications about data frame, coordinates and projections.

I do not use GIS very often and I have a big gap in cartography.

I use ArcMap 10.2 Desktop

someone sent me a layers package. I imported the layers into a new empty document.

The data frame now gets the layer's proj. coordinate system and projection.

-1) some layer in the layers pack have BRITISH NATIONAL Grid coord system and Projection:Transv.Mercator and other layers have GCS WGS84 Datum D_WGS84. Shall I have to change anything? Are they correct or because they have different coord system I will have problem (i.e doing some measurement or analysis?)

- 2) If I add some raster Admirality multichart a message for transformation comes up. It asks me if I want to transform the coordinate system as some of the charts are in ETRS_1989 Mercator and some are ETRS 1989 Transv Mercator. Shall I have to transform? If so, does it results in any measurement distortion or conflict with the layer package?

-3) I had to create a new feature class so I used the BRITISH NATIONAL GRID Transv.Mercato because of the Data Frame.Am I correct? Does it result in any measurement or spatial analysis  problem?

-4) I tried to edit my new feature class and a kind of info box comes up with "Spatial reference does not match data frame" related to the layers which were in GCS WGS 84 instead of British National Grid. Is this a problem?

 

Thank you very much in advance to who will have time to clarify.

Have a nice day

 

Francesca

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