I have coordinates in decimal degrees and need to calculate area for polygon objects. I tried to use AreaCalculator and set up criteria to find all these bigger than 100 sqm. But result is not as I expected. Should I convert first from decimal degree to metric?
[GIS] Calculate area with FME
fme
Related Solutions
You can use LineJoiner transformer with parameter List Name. But you need to do some additional data processing:
- Use
LengthCalculatorto calculate lengths. - Use
Sorterto sort your lines by length (numeric sort, descending). - Use
LineJoinerto join lines. The biggest ones first (thanks to step 2). Specify parameterList Nameof theLineJoiner- some name for new list attribute. - Use
ListIndexerwith list index 0 - to get the first joined feature (the biggest one) attributes' from the list.
Here is how it will look:
EDIT1:
In order to be able to join only <1m features to bigger ones we need additionally to use:
Testertransformer after LengthCalculator with test:_length < 1- Use
SpatialFilter(tests to perform parameter:TOUCHES) after Tester to filter only that features which touch features <1m. Then perform line joining on them together with <1m features. Features that don't touch <1m, direct to output (or further processing).
Model:
EDIT2:
If you have <1m line that touches two big ones then they all will be joined together. If such case (<1m feature touches two or more big ones) is possible in your data then you should add some processing of such cases. Take a look at parameters Merge Attributes and Attribute Prefix of transformer SpatialFilter. Using these parameters you should be able to detect such cases and then do some additional filtering.
EDIT3:
Let's solve the case when you have two big lines touching one small (<1m). We need to take only one of the big lines to participate in joining with small one.
In order to be able to perform such filtering we need to mark these two big features with some id from small one they are touching. As stated in EDIT2, it can be done in SpatialFilter transformer using parameters Merge Attributes and Attribute Prefix.
Then use transformer DuplicateRemover to filter such duplicate features (two big) and take only one of them.
Hint: try to use Inspector transformer during creating your model and view intermediate results in any case that is not clear to you. In such way you will better understand how each of the transformers are working. Experiment with your data! :)
I believe you can use LengthToPointCalculator transformer. But you have to do some additional preparations:
- Extract point coordinates to attributes with
CoordinateExtractor. - Merge line feature with points (
FeatureMerger). You need to receive one feature for each point with line geometry and original point's coordinates in the attributes. UseGeometryExtractor/GeometryReplacer.
Model will be similar to:
You can download my test model with data here: example.
Best Answer
Yes, reproject but use
_AZMEA_as the coordinate system. It's a dynamic equal area projection designed exactly for this. Then simply reproject back. In future the AreaCalculator will have an option to do this reprojection automatically.