If you ever get the opportunity to work with bathymetric data, you may encounter CARIS files. CARIS is an enterprise GIS suite that is well suited to marine and hydrographic applications. Many GIS offices don’t have access to CARIS, but that doesn’t mean the data is out of your reach. CARIS offers a free data viewer which you can use to export the data to a more versatile format – ASCII text.
The first thing you’ll want to do is download the CARIS EasyView program. You’ll need to provide name and contact information, and you cannot download the program until you’ve received a confirmation code via email. Installation is typical for Windows programs, and opening the CARIS file (which will probably have a .car or .car0 extension) is fairly straight forward. The first thing to do in EasyView is select File > Export Surface to ASCII, which brings up the following dialogue box:

Figure 1: CARIS EasyView export dialogue
If there are multiple surfaces in your file, you’ll have to export them one at a time, by selecting them in the dialogue box. In my file, there was only one surface to convert, so picking the right one was easy. You’ll want to set the position units to Geographic DD – decimal degrees. Although my data had a number of different features which I could output, I was only really interested in the depth. Include any features in the output file by adding them from the list on the left to the list on the right. One of the key attributes to choose here is the delimiter. I chose the comma, making the output file a de facto CSV – which is readable by both ArcGIS and major spreadsheet programs. My research indicates that the final attribute, Z-axis convention, has no effect on the data output – but it’s probably best to stick with “Up is positive” just in case.
The textfile created by this process is a comma delimited set of coordinates.
As an example, from the file I was working with:
44.031723N,076.495925W,8.872
44.031723N,076.495925W,8.817
Unfortunately, these numbers are not very useful to us, as ArcGIS uses negative numbers to represent longitude west. The combination of number and letter in the latitude and longitude fields will make projecting and manipulation difficult. And it’s better to have negative depth values (and positive altitude values). So I’m going to use awk, a command-line tool, to process the file:
awk ‘BEGIN {FS = “,”; OFS = “,”} {print $1*1,$2*-1,$3*-1}’ carisexport.txt > carisawk.txt
Without getting into too much detail, this multiplies the first column by 1, and the second and third columns by -1, using a comma as the field separator. (Multiplying an alphanumeric string by a number in awk recasts the variable as a number.) Now we need to add simple headers to the file, signifying names for each field. Open the file in a text editor – Windows Notepad will probably reject the file for being too long, so a more functional text editor (such as EditPad Lite) is required. Latitude, longitude, and depth are good names for the fields. Here’s the first 3 lines after running awk and adding headers:
latitude,longitude,depth
44.031723,-76.495925,-8.872
44.031723,-76.495925,-8.817
Now the file can be opened using Tools > Add XY Data in ArcGIS. Select latitude as the Y Field and longitude as the X Field, and don’t forget to define a projection. Export the layer as a shapefile, and it can be plotted, rasterized, or spatially analyzed as you see fit.
If anyone from CARIS is reading this, it would be very helpful if you added simple headers to the ASCII export function, and used standardized representations for latitude and longitude values. Maximum compatibility with companion tools is a strong selling point for any proprietary software.
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