[Qgis-user] On format and coordinate systems transformation

[Mats Elfström]

Hi Group!

I will begin this post with a disclaimer. This is no advertisement, or
endorsed statement. I intend it as friendly advice to fellow professionals,
for the good of the industry and our reputation.


Many posts on this list come from users who struggle to move geodata
between software systems or projections and coordinate systems. Several
times a week or even per day, more or less tricky conversion problems are
aired. This is a good thing. It shows that more people are using more
geodata, and wants to combine data from various sources. This is one
important purpose of a GIS.


However, format conversion and coordinate transformation can be tricky
business. If performed improperly, or with inadequate tools, mistakes can
result in loss of information, or distorted or misplaced features. Such
errors may be apparent, but can also go unnoticed, and later reflect badly
on the person or institution that supplied the data.

While I appreciate that all data handling tips on this list are given in
good faith, I have seen those that are outright wrong, difficult or even
dangerous, and not in line with what I judge to be Good Practice of our
trade.


 There is really only one professional and system independent tool for all
kinds of spatial data conversion, and that is FME from Safe Software. I
would recommend no other. Only FME can safely handle the multitude of
coordinate systems and the ever-evolving types and versions of file
formats. Add to that the ability to extract, validate and combine data from
different sources into a single workflow. The Workbench, where you
graphically build your workflow is one of the best GUI:s I know.  You can
build very complicated workflows and save them for later use. For recurring
conversion tasks, this ensures that each data transfer is performed exactly
like before.  Workbench files can be built by FME and GIS pros, and
distributed for the use of others who just needs a task done.


Quality does not come cheap, and I realize that the cost of FME can seem
prohibitive. However, if you take into account the time and effort that
people must use to try to tweak this tool here, or find that script there,
with perhaps unpredictable results; you may find that the money for an FME
license is well spent. On the other hand, consider the risk that lost or
distorted information leads to costly damage further on in the chain.

Whenever I attend a seminar or conference on GIS/GIT/mapping and surveying,
people mention FME as an everyday tool:  “Oh, and then we of course have
some FME scripts to process the data.”

The support from Safe Software is excellent. They depend on that their
tools can be used, so problems and suggestions for improvement are dealt
with promptly and kindly. There is always a fresh beta build available to
try out the latest fixes or additions.

Visit www.safe.com to find out more, and note that any flavor of FME
Desktop can be downloaded for a free 14 day trial.


Best Regards, Mats.E
______________________________________________
GisKraft, GIS och webkonsult
Mats Elfström, Väpplingvägen 21, SE-227 38 LUND, Sweden
tel: +46 70 595 39 35 / web: www.giskraft.com
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