Modules to support z coordinate from geometry

[DenisCarriere]

Proposing

Enable modules that require having a z coordinate be able to retrieve this altitude data from the 3rd coordinate of the GeoJSON geometry [x,y,z]. The z param would still be available to retrieve the altitude from properties, however this would now be optional.

Modules

List of modules that should be able to manipulate z coordinate directly from geometry.

• @turf/isobands
• @turf/planepoint
• @turf/tin
• @turf/isolines
• @turf/idw
• Missed modules??

Any thoughts?

CC: @marie15 @morganherlocker @tmcw @stebogit @rowanwins

[marie15]

You didn't miss any modules, nice. But my problem is I don't have z coordinate, so how can I get this coordinate?

[DenisCarriere]

@marie15 Z coordinates is defined by elevation/altitude, that would be retrieved from your own personal datasets, TurfJS won't be able to help you calculate datasets without this information.

[marie15]

As I said before I don't have this information, how can I get this coordinate from latitude and longitude? Thank you 2017-03-28 17:51 GMT+00:00 Denis <notifications@github.com>:

…

@marie15 <https://github.com/marie15> Z coordinates is defined by elevation/altitude, that would be retrieved from your own personal datasets, TurfJS won't be able to help you calculate datasets without this information. — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#628 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/ANe_70pmFwgoyzyysKXeQJfhy3IlJZ0Uks5rqUiSgaJpZM4Mo0DQ> .

[morganherlocker]

@marie15 You will need to source this information yourself and implement your own method of querying the value at a coordinate. This is outside the scope of Turf, but I would do some web searching and check out datasets like those provided by USGS. This data is normally delivered in a bulk raster format like a DEM, which is not the type of data that Turf is designed to handle.

[marie15]

I understood, thank you for clarification, I will do research about what you suggested. 2017-04-05 0:48 GMT+00:00 Morgan Herlocker <notifications@github.com>:

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@marie15 <https://github.com/marie15> You will need to source this information yourself and implement your own method of querying the value at a coordinate. This is outside the scope of Turf, but I would do some web searching and check out datasets like those provided by USGS <https://nationalmap.gov/elevation.html>. This data is normally delivered in a bulk raster format like a DEM <https://en.wikipedia.org/wiki/USGS_DEM>, which is not the type of data that Turf is designed to handle. — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#628 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/ANe_72bjNQC9avHqoZzzZIyq8dlNFW-cks5rsuT1gaJpZM4Mo0DQ> .

[DenisCarriere]

Ref: #628 #2

[rowanwins]

My only general comment on this is that there are probably a stack of modules that simply override the coordinates that come in, discarding any data that may be within the 3rd position in the array.

[DenisCarriere]

Agreed, however if your data does contain [x,y,z] then this would be useful, both properties & the 3rd coordinate should work for these modules, so you can always fallback to GeoJSON properties if the data gets stripped.

[dpmcmlxxvi]

@DenisCarriere I looked over @turf/idw and it doesn't seem to use the z-coordinate as a parameter. It is assigning the output of the interpolation to a new property properties.z. However, that doesn't seem to have anything to do with the z coordinate.

I think it is a bad property name. The documentation states that the new property should be called IDW. So that appears to be a bug. Will add bug report if you agree. Fixing it would require renaming the output property name which wouldn't be backward compatible.

[DenisCarriere]

@dpmcmlxxvi 👍 sounds like a plan

[dpmcmlxxvi]

@DenisCarriere Unless there are other modules I think this can be closed. tin is done per #772 and idw doesn't apply per #774.