Software Review: Safe Software's FME Desktop Translator/Converter
Professional Surveyor Magazine - September 2009
James White, PLS
FME is a spatial ETL solution by Safe Software, Inc.
(Spatial ETL tools provide the data processing functionality of traditional extract, transform, load [ETL] software, with a primary focus on working with data.). FME can read and write data in more than 225 formats and can apply several hundred different types of transformations.
For example, FME can read in a geo-coded JPEG-2000 aerial photo in the UTM coordinate system and write out a tiff file and accompanying WLD geo-reference file in whatever state plane coordinate system is needed. Likewise, it can read vector data, such as an ESRI shapefile, and combine it with a CSV file of monument coordinates for writing out to an AutoCAD file. FME is designed as a batch processor: once you have set up a transformation, it can then be used to translate an entire set of files in one shot.
The primary user interface is FME Workbench (Figure 1
), although a data viewer and data translator are also included. For simple format changes, a wizard leads you through step by step. The basic concept is that there are data readers and writers for each format and also data transformers that can further manipulate the data. If you connect a reader to a writer of a different format, then the files are converted automatically. FME has a multitude of transformers, each one doing its own specific manipulation, such as resample raster data, convert datums, calculate statistics, or even TIN and contour data.
For example, to convert a GeoTIFF raster file to a JPEG file is easy: just show it the source file, show it the desired output format, and FME does it. As a GeoTIFF has coordinate information in its header that has no place to go in the JPEG format, a WLD file is written with the geo-referencing information. This conversion can also be modified to other similar tasks, such as stripping only the geo-referencing data out of the images into an excel spreadsheet or tagging non-geo-referenced image files.
Here's a more complex example. For next month's review I needed a map of assessors' parcels as an ERSI shape file, in WGS84 datum. My initial file was an ACAD drawing of polylines that I had previously stripped from tax mapping and compiled into one drawing, which was in NAD27 state plane coordinates. To obtain the desired results, I first started with the translation wizard in FME Workbench to change the format from ACAD to shapefile. As the ACAD file has no internal indication as to what datum it is in, I had to process it through a "datum setter" transformer. To do this I picked the processor from the list, then dragged it across the workspace so its input was connected to the source data file outlet, and then changed its property to show that the data is NAD27, NYE3101 in feet (Figure 2
). I then added the "reprojector" transformer using the same steps and changed its properties to show that I wanted it to convert to the WGS84 datum. With the workspace all set up, as many files as I want can be converted.
Let's take the example a step further. If I had not already stripped and compiled the parcel polylines into one drawing, FME could have gone through all of the drawings in the directory (each representing a tax map sheet), pulled out just the parcel shape polylines, and done the conversion (that would have taken several hours of manual work) in only a few minutes. FME could also have gone through the tax maps, matched the text string of the tax ID numbers for each parcel with the surrounding polyline on the parcel layer, grabbed associated data (such as a street address or owner name) out of a spreadsheet, and written it all to a Google Earth KML file.
FME can also convert data from text files into any of its known formats. One example would be to read an ASCII file of coordinate values and then write out an ACAD drawing file where all points with the same descriptive code are connected by linework. FME has a strong user support group (at www.fmepedia.com
) that has written many transformers for specific file formats and then made them available on the user community site. I was able to download a transformer that processed GPS-based NMEA format file and could then convert the track data to state plane coordinates. The text file processors are very flexible and could easily be used to extract data out of an old, obsolete data collector file format and convert it into a usable format. If you look at some of the sample translators, you can imagine the complexity of the tasks FME can perform.
FME can be licensed several ways and with several different flavors to meet specific applications. The "FME Professional" fixed seat license that I reviewed starts at $2,250 but can range up to $10,000 for floating license for specific applications. FME technology is also available in an enterprise server environment with FME Server.
Overall, FME is a very comprehensive and flexible tool. If you need to deal with files coming from various sources in differing datums and combining in attributes, FME can help merge them all into a usable format.
For FME resources, visit the central portal for its user community, called www.fmeusercentral.com
About the Author
James White, PLSJim White owns a private practice in Schenectady, New York that provides surveying and software development services.
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