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Wasmer Consulting - NMPlot - User's Guide - Quick-Start Guide to Importing Data into NMPlot


NMPlot User's Guide, Appendix G: Quick-Start Guide to Importing Data into NMPlot

NMPlot is a powerful application for working with grid data sets. If you would like to use NMPlot to work with your data, you must first put it into a format that NMPlot can import. This appendix is a quick-start guide to doing so with a minimum of effort.

The easiest way to import your data is to create a text-based NMGF grid file. The NMGF format, while powerful and well-documented, can be somewhat intimidating when all you want to do is create a simple grid file. Therefore, this appendix describes the bare minimum necessary to do so.

Note:

If you are using NMPlot as part of a third-party application (BNOISE2, INM, NOISEMAP, ROUTEMAP, SARNAM, SIPS, or TNM), you can skip this section, as these applications write files that NMPlot can read directly.

What is the bare minimum I have to do to create an NMGF file?

Create a text file with the following text, replacing the sample data points with your own.

{TITL Grid Vers 2 3}
{DPAL 5
    (-90.02, 45.00) 50.0
    (-90.02, 45.02) 50.0
    (-90.00, 45.02) 50.0
    (-90.00, 45.00) 50.0
    (-90.01, 45.01) 60.0
}
{ENDF}

The first and last lines, beginning with {TITL and {ENDF, denote the beginning and end of the data set. They must appear exactly as shown.

The middle seven lines specify the actual data. The line...

{DPAL 5

...specifies that 5 Data Points with Arbitrary Locations (DPAL) follow. Each data point is specified by a location (the numbers in parentheses) and a data value at that location (the numbers after the parentheses). The locations are specified in decimal degrees of east longitude and north latitude. West longitudes are negative, so the point (-90.02, 45.00) is at longitude 90.02 degrees west, latitude 45.00 degrees north.

Do I Have To Use Longitude and Latitude to Specify My Data Point Locations?

No, you can use Cartesian coordinates to specify locations. Add the following line just after the line that begins with {TITL.

{CART -90.0 45.0 0 0 METR 0}

This specifies that all locations will be given in meters east and north from longitude 90.0 west, latitude 45.0 north. If you want to use feet, replace METR with FEET.

Here is the modified example file.

{TITL Grid Vers 2 3}
{CART -90.0 45.0 0 0 METR 0}
{DPAL 5
    (  0,   0) 50.0
    (  0, 100) 50.0
    (100, 100) 50.0
    (100,   0) 50.0
    ( 50,  50) 60.0
}
{ENDF}

How Do I Specify The Physical Units of the Data Points?

Add the following line just before your data points.

{MTRC "Air Temperature" "F"}

The first quoted text string describes what is being measured. The second specifies the physical units.

Here is the modified example file.

{TITL Grid Vers 2 3}
{CART -90.0 45.0 0 0 METR 0}
{MTRC "Measured air temperature" "F"}
{DPAL 5
    (  0,   0) 50.0
    (  0, 100) 50.0
    (100, 100) 50.0
    (100,   0) 50.0
    ( 50,  50) 60.0
}
{ENDF}

Can I Add More Detailed Notes About My Data?

Yes. Add the following lines just after the line that begins with {TITL.

{SORC "Measured"
    {DESS "Measured air temperature at 1 meter above ground level"}
    {DESL "Measurements made using a ACME model X34 thermocouple"}
}

The quoted text after SORC specifies the broad category of the data's origin. It can be any text, but it is suggested that "Measured" be used for measured data, and "Model" be used for the output of numerical models.

The quoted text after DESS is a short description of the data in the file. If possible, it should be kept under 60 characters in length. This text should be appropriate for use as, say, the title of a contour plot of the data.

The quoted text after DESL is a long, detailed description of the data in the file and any notes you wish to add. It can be as long as necessary, and can contain line breaks.

Here is the modified example file.

{TITL Grid Vers 2 3}
{SORC "Measured"
    {DESS "Measured air temperature at 1 meter above ground level"}
    {DESL "Measurements made using a ACME model X34 thermocouple"}
}
{CART -90.0 45.0 0 0 METR 0}
{MTRC "Measured air temperature" "F"}
{DPAL 5
    (  0,   0) 50.0
    (  0, 100) 50.0
    (100, 100) 50.0
    (100,   0) 50.0
    ( 50,  50) 60.0
}
{ENDF}

Where Can I Get Additional Information?

The NMGF standard has many additional features that you can use to describe and annotate your data. To learn more, visit the NMGF web page, http://wasmerconsulting.com/nmgf.htm.


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