Reading in .tif using readgeoraster

Hi all,

I am trying to read in a raster DEM in .tif format using readgeoraster and am having some trouble. The code I am using is:

[A,R] = readgeoraster('postSally_breachFill.tif');

A=double(A);

When I look at the values in A and visualize it using :

mapshow(A,R)

There are numerous -99999 or NaN values when the file does not have any NaN values when visualized in ArcGIS (values range from -13 to 12). Is there a reason it is unable to accurately pull in the correct elevation values? I have also tried

[A,R] = readgeoraster('postSally_breachFill.tif','OutputType','double');

Any help to get the accurate values would be appreciated!

I have tried adding in pictures to show the difference. Perhaps it is a resolution issue?

[KSSV]

May be ARCGIS replacing those values with zeros.

[Autumn P]

Can you elaborate a bit on that? What do you mean? 0 would represent sea level not NaN.