Exporting matlab matrices to ESRI ArcMap

I have a large (4499x1459) 2D matrix containing surface ocean current data, and want to create an ArcMap shapefile from the matrix NaN values (i.e. a land mask). I have a code which creates polygon vertices (lat, lon) for each NaN value cell, but this is taking too long to do for such a large matrix. Is there a way I can simply read the matlab matrix into ArcMap as a raster image, so I can then convert it to a vector format there?

I have had no luck with this in searches so far.

Thanks in advance.

Answer 1

[Walter Roberson]

A thought: bwboundaries(isnan(YourMatrix)) would construct pixel lists; the pixel lists would be the vector coordinates. Not optimized to remove pixels that are in straight lines between pixels, but perhaps that is not needed at this time.

I do not know the performance of bwboundaries(), but it might be worth trying.

[Sally]

Hi Walter,

thanks for your answer, this gives me a boundary for my land mask very quickly. However, the results are not in a format I know how to use. Do you know how to then create a boundary file from the resulting image?

Thank you, Sally

Answer 2

[Rob Comer]

ArcGIS can read GeoTIFF format. If you have R2011a, perhaps you could write your ocean current grid to a GeoTIFF file using the Mapping Toolbox geotiffwrite function, then import it into ArcGIS. See:

http://www.mathworks.com/help/toolbox/map/ref/geotiffwrite.html

[Sally]

Oh that looks amazing, unfortunately I don't have that version. I am using 2010b.

Thanks anyway Rob.

[Matthew Cooper]

Also, it is not clear from the documentation how geotiffwrite handles NaN values - can you clarify? In my experience, when I use geotiffwrite to write Matlab matrices with NaN values into a .tif file, the NaN values are converted to NoData values such as -1.38E-38, however when I load the .tif's into ArcMap the NoData value is not recognized. Arc has tools for setting NoData, but they are in the Spatial Analyst toolbox that I do not have authorized.

Any idea how to solve that problem?