Home/Blog /How do you know which Transformers to use!? There are so many! Part 2

How do you know which Transformers to use!? There are so many! Part 2

For a beginner FME user, with over 300 Transformers, finding the right Transformers to get the job done can seem like a daunting task. Even for more seasoned FME-ers, finding the right Transformers can still be challenging, and we might not be using the most efficient or effective ones for what we want to do.

As an FME trainer and consultant, I often hear comments such as, “But there are so many! I don’t know how I am ever going to be able to find the ones I need…” “That was so quick, how did you know what to use!?” There is an easy answer to that question: experience. The more you use the software, the easier it becomes. However, that response doesn’t really help when you are just starting out. So, I will share with you the process I go through to find the right Transformers in hopes that it might shed some light on the question…

1. Break it down

Okay, so you know what data you’re starting with, and you know what you want your final result to be. Most of the time, there isn’t just ONE transformer that is going to help you out. You need to break down your process. Utilis

Here are a few questions to help you do just that…

  • Do I want to transform the CONTENT or STRUCTURE of the data? In other words, do I actually want to change the data itself or do I want to change the way it’s organized?
  • Is the change I want to make SPATIAL or ATTRIBUTE based? Do I need to change the actual geometry, or just the attributes associated with it?
  • Do I need to compare different datasets with each other?
  • Do I need to filter data out of my dataset?
  • Am I working with a particular kind of data? 3D? XML? Database?


Once you’ve broken down your process into smaller tasks, now you can start hunting for Transformers. Our friends at Safe have actually divided up the transformers into categories for a reason – so that it’s easier to find them.

The questions that you asked yourself when you broke down your process will help you figure out which category to look in… some examples of categories are: Filters, Calculators, Rasters, XML, Geometric Operators etc…

Example: If you know you need to filter your data based on an attribute before further processing, check in the “Filters” category. If you know you need to reproject your data, check in the “Coordinate Systems” Category.


As of 2014, each element in the canvas (Transformers and Feature Types alike) has a help file associated with it, that will pop up in the help tab at the bottom of the Workbench. This is actually EXTREMELY useful. I often check the Help, even for Transformers that I am used to using, just to double check how to set up the parameters and input and output ports. This can also help you decide if the transformer is right for your process, or not.

4. Search for what you need.

In the Transformer Gallery, there is a Search functionality, which will search the text of the help files. Depending on how good you are at searching (and if your vocabulary is aligned with that of Safe…), you may or may not have success. Feel free to use the search and click through the transformers, reading the help, until you find the right one for you.

5. Don’t be afraid to try it out.

With FME, a little trial and error never hurt anyone, or any dataset, that is. You can run your process as many times as you want until you get it just right.

Some tips for testing…

  • Use the “Redirect to Inspection Application” in the writer menu to make sure that you don’t alter your destination dataset.
  • Or simply don’t connect your Writer, and add Inspector transformers instead.

More question or need help with FME? Contact-me

Allison Hughes

Consultant in Geomatics

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