SEF Import Issues

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When you convert SEF files to theCOMPASS format, some files will not be converted perfectly. There are several reasons for this. For one thing, the "SEF" file format is very complicated and each survey program interprets the standard slightly differently. Also, each cave survey program is different and these differences are reflected in their data structure. For example, some survey programs don't save a Cave Name or Survey Name with each survey. This means that to import data from one of these programs, the converter must guess at the Cave Name and Survey Name.


Here are some of the issues you need to be aware of during the conversion process:


1. Directory Structure. SEF files contain information about how the survey data will be organized. This organization will be reflected in the Compass Data Files (.DAT) and Project Files (.MAK). Since every program handles this structure differently, some data from other programs will require reorganization before Compass will be able to process it properly. For example, some programs can put several different, unrelated caves in the same structure. If you import this type of data into Compass, you will have to separate out the individual caves before the plot will make much sense. As a result, the Compass import program gives you the option of putting each SEF directory into a separate Compass file.


Also, SEF directory names can be up to 40 characters long. Compass deals with SEF directories by putting each directory into a different file. As a result, the Compass import program derives its filenames from the from the SEF directory names. Since Compass still supports a DOS version, it is limited to having filenames with only eight characters. For this reason, the conversion program compresses the SEF directory name by removing non-alphanumeric characters. The first eight characters of the compressed directory name are used as the filename. For example, if the SEF directory name were "Water Tower Cave" the Compass filename might be "WATERTOW.DAT"


In some instances, two different SEF directories will be compressed into the same Compass file name. For example both "Water Tower Cave" and "Water Town Cave" would result in the same Compass data file name: "WATERTOW.DAT." The conversion program handles this problem by adding a numerical extension whenever it finds a duplicate file on the disk. Thus, in our example, one file would be named “WATERTOW.DAT” and the other would be named “WATERTOW.001” When the program finds a duplicate file name, it will display the following warning message:


WARNING- Duplicate File: WATERTOW.DAT  In File: CAVES.SEF Line: 68


Because of this problem, the conversion program has the option of creating unique filenames.


2. Survey Names. SEF files do not support survey names in the same way as Compass. In Compass, the survey name corresponds to the letter prefix of each station name. For example, if the survey name is "AB" then the station names will be AB1, AB2, AB3 etc. Some other programs treat survey names more like comments using names like: "The Big Room Survey". (Compass has a survey comment field that is used for this type of information.) The conversion program does its best to generate survey names from the data, but it does not work perfectly. After you converted a file, you'll probably want to rename each survey and check for duplicate survey names in the survey editor.


3. Make files and Linking Stations. Compass Project files are used to combine multiple data files into a single cave system. Some survey programs allow multiple caves in the same SEF file. It is very common when you have two or more caves, that there will be duplicate station names between the two caves. For example, most cave surveys start with the "A" survey, so the chance of having duplicate "A1" station is very high.


COMPASS's method of dealing with these duplicates is to create linking stations between the two caves. These "Links" have the effect of isolating the caves from each other, so that the duplicate station names do not interfere with each other. If you are converting SEF files with duplicate station names, you will have to create links or else the images will show strange looking long shots between different sections of the plot.