Using the UpdateDetector with ArcGIS Online Feature Service

Hi

 

 

For issues like this, I normally try to isolate one single feature from both datasets and only work with these to try and understand what is going on. You can e.g. use a Tester on the ObjectId from each dataset and send the Original and Revised feature to the Data Inspector. Using the Feature Information pane, carefully analyze and compare the following between the two features

• Coordinate system
• Dimension (2D/3D)
• Number of vertices
• Extents
• The attributes "fme_geometry" and "fme_type"
• For multipart geometries, the number of parts
• The all of the above are completely identical, you will have to analyze the difference coordinate by coordinate.

In particular, you should look out for rounding differences introduced by saving and re-reading features from SDE, as the coordinates might have changed very slightly by the tolerance, precision and extents settings of your feature classes (the so-called "snapping grid"). To fix this, first make sure that your feature classes in SDE and your file geodatabase have exactly the same definitions (check with ArcCatalog), alternatively use the ArcSDEGridSnapper in FME on both datasets before the UpdateDetector to align them to the same grid before comparing.

 

 

David

 

 

Hi David,

 

 

Thanks for replying. You are correct, it's something to do with the coordinates they are slightly different and when they get compared this slight difference is flagged as updates. I've attempted to use the ArcSDEGridSnapper as you've suggested but I haven't been having much much luck. I still can't get the coordinates to line up just right. Do you have any other suggestions on how to get them to match or some other work around?

 

 

Warren

warren156 wrote:

Hi David,

 

 

Thanks for replying. You are correct, it's something to do with the coordinates they are slightly different and when they get compared this slight difference is flagged as updates. I've attempted to use the ArcSDEGridSnapper as you've suggested but I haven't been having much much luck. I still can't get the coordinates to line up just right. Do you have any other suggestions on how to get them to match or some other work around?

 

 

Warren

Hi @warren156, I am experiencing the same issue as you. Did you ever have any luck solving this?

 

kirstynalex wrote:

Hi @warren156, I am experiencing the same issue as you. Did you ever have any luck solving this?

 

Hello @kirstynalex

 

 

I would suggest taking a look at the CoordinateRounder. That seems to be the common place where 'changes' will show up when you are not expecting any between features. Depending on the level of precision you are hoping to maintain. Rounding to 4-6 decimal places may achieve the similarity that would allow features not to be displayed as 'updates'.

 

 

Hope that helps.

trentatsafe wrote:

Hello @kirstynalex

 

 

I would suggest taking a look at the CoordinateRounder. That seems to be the common place where 'changes' will show up when you are not expecting any between features. Depending on the level of precision you are hoping to maintain. Rounding to 4-6 decimal places may achieve the similarity that would allow features not to be displayed as 'updates'.

 

 

Hope that helps.

Thanks @trentatsafe, that worked beautifully! :)