Hi everybody,
Let me preface my question by saying that most of what I do in ArcGIS Pro, Field Maps, and ArcGIS Online has been self-taught. I am not a programmer and do not have any previous programming experience. I'll do my best to explain my problem with the correct terms, but there's a good chance I'll misuse or mix up terms, and I want to apologize in advance for that. I promise I'm not being dense on purpose - sometimes the terms used in the ESRI world aren't always very intuitive, so occasionally it's hard for me to grasp them.
Here's my issue:
I create maps for use in the Field Maps application using ArcGIS Pro, and I publish them as Web Maps. In ArcGIS Pro, my default length unit settings are set to feet. I can check this by looking on the Project tab, under Options, then Units, then Distance Units. Foot is selected as the default. These are the settings used when I publish a Web Map to ArcGIS Online.
The workers who use these maps have collected linear features on the map using the Field Maps application. I'm not sure if it matters or not, but I'm pretty sure they used the "stream location" feature to trace their steps as they walked out the length of the feature. Once this linear feature is created, the Shape_Length field is automatically populated, and that's great. It's very useful to have live, always updated information available to the workers in the field without having to manually calculate the geometry of a field after-the-fact (which I'm not even sure can be done from either the Field Maps application or ArcGIS Online - if I'm wrong, I'd love to be shown how to do this).
The problem is that the unit for Shape_Length appears to be meters now. Manually measuring the distance using the "Measure" tool shows a much larger value in feet - larger by a factor of essentially 3.28.
I'm not sure if there's a way to check this in ArcGIS Online. When I open the map again in ArcGIS Pro (by downloading a .pitemx file of the map, which is what happens when you click "Open in ArcGIS Desktop" in ArcGIS Online and select the "Open in ArcGIS Pro" option), the values in the Shape_Length field are still the same as they were in ArcGIS Online - meters - but checking the default distance unit setting still shows Foot as selected.
So what am I missing here?
Did I miss a step in the map publishing process to keep the Shape_Length units as feet? Do I have the option to change the default unit for Shape_Length in ArcGIS Online or Field Maps after the map has already been published? Is there any other option for a live, always updated field showing the distance of a linear feature in feet, or will I be forced to add another field for length and then manually calculate the geometry after-the-fact?
Thanks in advance for any help. If I've confused anyone by using the wrong terms, please let me know and I'll do my best to clarify.
When you publish to ArcGIS Online via ArcGIS Pro, it is storing the data using the Spatial Reference System of the map. You can see this by opening the map properties and selecting "Coordinate System" Click "Details" and look for the Linear Unit value. In the example below, it is using a State Plane US Feet system.
If you want the service to store as meters, you will need to set a CS that has meters as the Linear Units.
Hi Tony,
Thanks for the response. I was under the impression that Web Maps could only be shared with the WGS 1984 Web Mercator (auxiliary sphere) coordinate system. I see now that the default linear unit for this coordinate system is meters. Is there any way to adjust this, or is this something that can't be changed?
If you upload files to AGO to publish, it will use Web Mercator. ArcGIS Pro uses the Map CS. You can change this in the Map properties, under Coordinate System. You can search for the desired system to use. Just make sure that the one you choose has feet as the Linear Unit and it is a good fit for the spatial extent of the data.