Why are Modelbuilder "Bearing Distance To Line" results different from manually drawn direction/distance function

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06-24-2018 03:06 PM
RobertReyes
New Contributor II

I created a model to plot a line for specified distances along a specified azimuth, then plot another line from the end vertice of that line for a specified distance in a perpendicular direction, then generate a point from end point of the second line. I used the “Bearing Distance To Line” tool to pull from a table that lists degree values to four decimal points (for example, 132.2458, 45.3789, etc.). The model seems to run fine, but the orientation of the automatically generated line is different from a manually generated line using the distance/direction function, even though the inputs are exactly the same. I thought maybe the projections were different for the two feature classes, but they are the same as well. I cannot figure out why this is happening or which result is more accurate, and was hoping someone might be able to help.

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kmsmikrud
Occasional Contributor III

Thanks Robert and Dan for all the responses. I'm going to look into the planar versus geodesic geometry differences for how that creates such different angle output for the lines created by the respective tools. I think that is good advice Robert on its a good practice to stick with one method for a project and document which method was used. 

RobertReyes
New Contributor II

Thanks, Kathy. It does seem incredulous to me too, that the angles diverged so widely from one another. I was working with distances of less than 300 feet and the lines still differed noticeably.

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kmsmikrud
Occasional Contributor III

Hi Robert,

I would like to submit an incident to ESRI. It was suggested it would help if we could tie it in with your incident number or so they could reference. Is this something you would pass along or still have? Thanks Again.

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RobertReyes
New Contributor II

That is great, Kathy! My ESRI case number was 02153535.

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kmsmikrud
Occasional Contributor III

Perfect, Thank-you!

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curtvprice
MVP Esteemed Contributor

I agree this is a bit of a hole in the documentation. The two methods are correct, but I am more comfortable with the editing method, as most survey calculations traditionally happen in projected space on plane (usually in state plane coordinates). I posted feedback to the help page on the tool to add some clarification. The tool help is very clear that they are doing the calculations in geodesic space (not on a plane) but it needs a statement that this is different from ArcMap and Pro editing.

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RobertReyes
New Contributor II

I also prefer the editing method; however, I have tables with hundreds of rows that contain start points, line distance, and line bearing and was looking for an automatic way to draw those lines. I used ModelBuilder, and the only geoprocessing tool I could find to generate lines was the bearing distance to line tool; as far as I know, there is no geoprocessing tool that can generate lines in a planar geometry. If there is a geoprocessing tool that does generate planar data, please let me know. BTW, when ESRI says that both solutions are “accurate,” they may be technically correct, but if I use both methods in a project and the end points for those lines fall in different locations, then they cannot both be “correct” relative to ground truth, each other, or the other data in the project.

DanPatterson_Retired
MVP Esteemed Contributor
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curtvprice
MVP Esteemed Contributor

Well, one could install ArcInfo Workstation and use COGO...  this is discussed in the help! 

I too am surprised this tool does not include an option to work in planar coordinates!

I wonder if the anyone over at Esri Surveying‌ has any thoughts on this?  

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