How to fix the size of a shapefile?

[MattMejac]

Hello,

I have a shapefile of selected countries across the globe, but when I add it to arcmap, it places the countries really small in the middle of the atlantic ocean on my esri basemap; the projections are the same.  How do I make the polygons (countries) in the shapefile bigger so that they line up with the basemap I am using?

Any help would be much appreciated!

Thanks,

Matt

[AnthonyGiles]

Matt,

That sounds to me that the original projections were not the same. If your countries are appearing really small in the middle of the atlantic ocean then the shapefile was probably originally in decimal degrees and your basemap is in web mercator. If somebody has just changed the projection of the countires and not actually reprojected the data that maybe causing the issue.

Try stripping off the projection info of your countires that add a new geographic WGS84 projection to them

[MattMejac]

Hi Anthony,

Thanks for your response; I should maybe have explained a little more about my countries shapefile.  the layer is of historical countries that I converted from an svg picture file into cad and than converted into a shapefile.  So it didn't have any spatial reference info other than the svg file was drawn in winkel-triple projection.  I do have a excel file with coordinates of the individual countries but not for the whole shapefile.  Any thoughts how to proceed?

Thanks,

Matt

[JohnFell]

Matt,

I believe that the initial conversion of your .svg image into CAD and then to shapefile did not capture the placement properties of the spatial features within the coordinate system correctly. This can be tricky when you are digitizing spatial features from an image or raster file and performing subsequent conversions. I would recommend revisiting the conversion from your .svg to spatial features using georeferencing in ArcGIS Desktop. You could use the basemap as the coordinate system source and "rubbersheet" the image on top of the basemap and digitize the historical country boundaries in. You  may have other layers that can provide other reference points or landmarks that will help in this process. I'm not sure which license levels provide the georeferencing capability but you might use this ArcGIS help document as a starting point.

[MattMejac]

Hi John,

The svg file didn't have any spatial information in it when it was converted to CAD and it was never digitized since it was never a raster.  The svg (scalable vector graphics) file preserved the country borders as polylines, and I then built the polygons from the polylines, hence they don't have spatial reference data.  I'm looking for a way to input the coordinates of the countries shapefile so that they can overlay current boundaries.

[JohnFell · Accepted solution]

Matt,

If you have access to the .svg file you mentioned in your post you should be able to use georeferencing to digitize the lines again. Georeferencing is the process of overlaying an unprojected image to some data source whether it be another image or some vector features. You select control points to tie down the overlaid image onto your source data to fit the way you feel that it should. Then, when the image is properly displayed on top of the projected data source, you can digitize your target spatial features in the coordinate system of your data source. I would recommend this approach. If you would prefer to adjust the spatial features rather than re-digitize them there are tools available in ArcGIS for this as well. In my experience this has been challenging and may not be feasible if you have hundreds of polylines.

[stefanstamenov]

Check the projections

[MattMejac]

im well passed that.

[JeffPace]

Really small in the middle of the atlantic seems like it was placed at 0,0.  You will have to either define projection on your shapefile, setting it back to the original projection, or if that does not work, redigitize.

A word for the future.  Dont take data out of ArcMAP into CAD, especially converting it to svg.  Scaling data will destroy the spatial attributes.  You need to keep your data in ArcMAP.

[MattMejac]

I never had it in ArcGIS; the data/maps were given to me in svg format (possibly made in Photoshop), hence the reason I am trying to convert it from svg to ArcGIS.  Nevertheless, I always appreciate tips!