Rich Map Format
Rich Map Format (RMF) is deCarta's proprietary and patented data format. It is a highly compact, binary format optimized for spatial query processing and lies at the heart of deCarta technology. In fact, some of deCarta's advantages derive directly from exclusive utilization of RMF.
RMF is partly a compaction (not compression) scheme. RMF reduces the "white noise" present in other data formats by a clever and efficient encoding of the data. Fixed-width fields clearly demonstrate the concept of "white noise". A fixed-width field of 25 characters is always 25 characters long regardless of whether any information is present. In the RMF, only useable information makes it in; "white noise" disappears.
RMF further reduces the file size by eliminating redundancies that can add many megabytes of redundant information in some formats. For example, a stretch of road may have the same name for nine segments. Instead of assigning the same name to each of those nine segments, RMF assigns the name once for a designated origin and destination.
RMF reduces the file size one more time by converting the data into a binary format. This compaction methodology results in file sizes that typically range from 1/10th to 1/15th the file size of the original source data.
The primary advantage of RMF is that it is spatially organized. A spatial format organizes data in a multi-dimensional fashion such that features near each other in reality get stored close together in the database. For example two gas stations located on opposite corners of an intersection, as illustrated in the following figure.
In a sequential file sorted by name, address, or street name, these points of interest (POIs) would be located at opposite ends of the data set with thousands, or even hundreds of thousands, of records in between. In a spatially organized format, the items are located adjacent to each other, just like they are in the real world. This means that once you find a location in a spatially formatted dataset, you can quickly find other close by POIs, addresses, features, etc.
Why should I use RMF?
RMF is specifically designed for location-based services and deCarta's products utilize RMF exclusively. Some of the advantages of deCarta technology derive from the optimized RMF in combination with the unparalleled speed and flexibility of the Drill Down Server.
How big is an RMF file?
An RMF file is typically 1/5th to 1/10th the original size. For example, a 100GB GDF file ends up as a 10GB to 20GB RMF file. This includes all of the indices as well.
The data is still there. It just has had all of the empty space squeezed out of it. The information is then compacted further by removing redundancies, efficiently encoding it, and then converting it to a binary format.
You obviously must be running some sort of compression scheme. Does uncompressing slow response times?
First, RMF is not compressed but compacted. Compact data is available for use as is. The compact data results in faster response times without loss of information or the need to uncompress it.
Can I use multiple datasets?
Map vendor independence is a key value proposition of deCarta's products. For example, you may you use one data vendor for North America and another for Europe. This is a "best of breed" solution.
What if I want a dataset you do not support?
deCarta supports the complete global coverage from vendors such as NAVTEQ, Tele Atlas, and AND. Other road network-oriented vector datasets can be created in RMF from Shapefile, Mid-MIF or similar GIS formats using deCarta software tools or Professional Services. Contact your account manager for more information.
I understand that my map dataset has to be in RMF, but do all my data have to be in RMF?
No, you may use specific data outside of the RMF. This is yet another advantage to using deCarta. Our technology allows you to store and access points-of-interest or other data from a relational database like IBM's DB2 or Oracle's 9i. deCarta's Traffic Manager also accepts traffic flow and incident data in non-RMF.
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