Storing measure value as integer

[MasaoMatsuoka]

AEGIST Guide book 2019 (page 45) says this about storing measure values as integer. I have a few questions about this recommendation.

To eliminate the problems caused by decimal measurements within the digital computing environment the Guidebook has adopted a standard LRM measure unit of M (the Greek letter mu), which is equivalent to 0.001 mile. This standard will restrict measure values to whole integer numbers. It is a simple matter to convert to decimal values by dividing a value by 1,000 at the time of publication, for those users who need this format. Some GIS platforms currently use this convention by internally converting measure values to integers.

 Questions:

1. Does Roads and Highways support this or doing this internally?

2. Do any DOTs actually store like this in Roads and Highways?

3. What is the recommendation in the context of Roads and Highways?

Thank you.

Masao Matsuoka (WSDOT)

Masao

[AmitHazra]

Hello Masao

Our ArcGIS Roads and Highways data model has very specific requirements for how the software discretely calibrates and interpolates measures across polylines. I would encourage you to review the following documents and links in determining the appropriate tolerance and resolution settings for your network LRMs relative to your distance measuring units and coordinate reference systems:

Data Model (Note Calibration Point requires a numeric data type Double): https://pro.arcgis.com/en/pro-app/latest/help/production/roads-highways/lrs-data-model.htm

Tolerance and Resolution Settings for the LRS: https://pro.arcgis.com/en/pro-app/latest/help/production/roads-highways/tolerance-and-resolution-set... 

Esri ArcGIS Geodatabase Feature Class Basic Spatial Properties: https://pro.arcgis.com/en/pro-app/latest/help/data/geodatabases/overview/feature-class-basics.htm 

-amit@esri  
Esri Transportation LRS Team

[MasaoMatsuoka]

Thanks for the detailed information.

In one of the articles Feature class basics—ArcGIS Pro | Documentation, it says "ArcGIS records coordinates using integer numbers and can handle locations with high precision." Are the M values stored in the same way as well? My understanding is ArcGIS internally store coordinate values as integer to avoid the floating point number issue. However, as you pointed out the calibration point store measure values as double. So I guess it won't help. So the answer to my original question is "No". Roads and Highways does not support AEGIST recommendation. I also read in another article there is a way to set the tolerance to something like 0.001 miles, but that is not recommended as it might introduce non-monotonic measures. The best we can do is to set measure to something like 0.0010000. However the value is stored as double so it might end up to be something like 0.0009876. So we need to round it before presenting to users. Am I understanding this correctly?

Thanks

Masao