Altering elevation values for an ASCII export

mjreed12

Greetings, I am trying to export an arc ascii grid but prevent values outside of a predetermined min and max from being passed on. Here is what I have so far:

GLOBAL_MAPPER_SCRIPT VERSION=1.00

//import ASCII data and ignore all values outside of the -5 to -65 range
IMPORT FILENAME="TG_004_BKSC_Caris.asc" \
TYPE=ARCASCIIGRID INC_ELEV_COORDS=YES MIN_ELEV='-5' MAX_ELEV='-65'

 // export the file as imported - ignoring the values less than -5 and greater than -65
EXPORT_ELEVATION FILENAME="C:\Users\surve\Desktop\Mike Reed\GM_scripts/Caris_test.asc" \
TYPE=ARCASCIIGRID GEN_PRJ_FILE=YES

The exported ASCII file includes all data and does not ignore the values outside of the bounds I have tried to set

bmg_bob

Hello,

The easiest way to get a good IMPORT command is to have Global Mapper do it for you as follows:

1. Load your data into Global Mapper
2. Use the Elevation Options | Alter Elevation Values tab to set the Maximum Valid Elevation and Minimum Valid Elevation
3. Save a workspace
4. Open the workspace file in a text editor such as Notepad.
5. Copy the IMPORT command (you will likely also want the DEFINE_PROJ ... END_DEFINE_PROJ lines also so you will have the correct projection information) to your script file.

Cheers,
Bob

mjreed12

Many thanks!

mjreed12

Bob,
   I am trying to alter this code to import altitude data from a SSS and need to remove the points that are out of spec for the job I am on, only keeping the data between 5 and 7.5m. Below are the Script Processing results from GM

Importing ASCII file PATH\SSS_M694_50m_XY-Alt.csv...

WARNING: Unknown COORD_ORDER value, X_FIRST will be used.

Exporting elevation data to file <SSS_M694_50m_XY-Alt_in-spec>...

ERROR: Elevation data must be loaded for EXPORT_ELEVATION command.

Here is my code;

GLOBAL_MAPPER_SCRIPT VERSION=1.00

//define the directory and filename needed for conversion

DEFINE_VAR NAME="DIR_TO_LOAD" PROMPT="DIR" ABORT_ON_CANCEL=NO

DEFINE_VAR NAME="FILE_TO_LOAD" PROMPT="FILE" VALUE="%DIR_TO_LOAD%" \

ABORT_ON_CANCEL=YES

//define the parameters for exporting a file to a user selectable directory

DEFINE_VAR NAME="DIR_TO_EXPORT" PROMPT="DIR" VALUE="1" 

//define newly exported file name

DEFINE_VAR NAME="FILE_TO_EXPORT" PROMPT= VALUE="_in-spec" \

ABORT_ON_CANCEL=YES

//import CSV file and ignore all values outside of the 5.0 to 7.5 range 

IMPORT_ASCII FILENAME="%FILE_TO_LOAD%" TYPE="POINT_ONLY" \

INC_ELEV_COORDS="YES" SKIP_ROWS="1" \

ELEV_UNITS="METERS" MIN_ELEV="5.000000" MAX_ELEV="7.5000000"

DEFINE_PROJ PROJ_NAME="UTM_ZONE19_WGS84"

Projection     UTM

Datum          WGS84

Zunits         NO

Units          METERS

Zone           19

Xshift         0.000000

Yshift         0.000000

Parameters

END_DEFINE_PROJ

// export the file as imported - ignoring the values less than 5 and greater than 7.5

EXPORT_ELEVATION FILENAME="%FILE_TO_EXPORT%" \

TYPE=FIRST_LOADED

I have banging my head against the wall for a couple days. Any help you could provide would be greatly appreciated! 
      Mike

bmg_bob

Hello Mike,

It sounds like you want to import a CSV file, including only points with elevation between 5.0 and 7.5 meters, then export the imported data to another CSV file. 

To do this, you need to use EXPORT_VECTOR, not EXPORT_ELEVATION. Your export command will need to be similar to this:

EXPORT_VECTOR FILENAME="%FILE_TO_EXPORT%" \
   TYPE=CSV EXPORT_ELEV=YES

This is a basic command for exporting a CSV file with elevations. There are more parameters available, so look at the documentation for EXPORT_VECTOR to see if there are any more that are specific to your situation.

Cheers,
Bob

mjreed12

Bob,
  Thanks for your explanation. There is still one issue and that is the way the import is written the filter is not working. None of the elevation values lower than 5 and greater than 7.5 are being filtered out. Thoughts?
   Cheers,
           Mike

mjreed12

Hi Bob,
  I have successfully written the script for vector data importing, which does not allow me to filter out the <5, 7.5< values during import and written a script for elevation data but it changes the values by gridding the data. Is there a way to write this for vector data and filter the inputs so I can prevent having to manually filter these readings?
  Thanks again,
          Mike 

bmg_bob

Hi Mike,

Another option is to delete the features that are outside the range you desire. You can do this using the EDIT_VECTOR script command. In your case, the command should look like this (assumes elevation values are in an attribute called "ELEV"):

EDIT_VECTOR COMPARE_STR="ELEV<5.0" COMPARE_STR="ELEV>7.5" COMPARE_OP="ANY" \
      DELETE_FEATURES="YES"

This command will delete the features with elevations less than 5 and greater than 7.5.  You can then perform your export.  

Cheers,
Bob

mjreed12

Hi Bob,

   I followed your suggestion above and was able to get that string to work BUT I dont want to delete the points I am filtering. I tried the MOVE_TO_NEW_LAYER command but it is not removing the outliers from the imported file, instead it just moves them to the bottom of the file that I am exporting. Maybe I am employing the string incorrectly?

EDIT_VECTOR FILENAME="%FILE_TO_LOAD%" COMPARE_STR="ELEVATION<5"  \ MOVE_TO_NEW_LAYER="YES" NEW_LAYER_NAME="-below-spec"

EXPORT_VECTOR FILENAME="%FILE_TO_EXPORT%-below-spec.csv" EXPORT_LAYER="-below-spec" \  TYPE="CSV" DELETE_FEATURES="YES"

Thanks again for helping me out with this!

   Cheers,
         Mike

    

bmg_bob

Hello Mike,

Something is not right in the processing for EDIT_VECTOR -- when Global Mapper copies the points that meet the condition in the COMPARE_STR, it also creates a line from those points. I will take a look at that to see what is happening. I think the commands below should move the points to a new layer and export them. Using SHAPE_TYPE on the EXPORT_VECTOR will make Global Mapper ignore the extraneous line feature that it created in the new layer.

EDIT_VECTOR FILENAME="%FILE_TO_LOAD%" COMPARE_STR="ELEVATION<5" COMPARE_NUM=YES \
            MOVE_TO_NEW_LAYER="YES" NEW_LAYER_NAME="-below-spec"

EXPORT_VECTOR FILENAME="%FILE_TO_EXPORT%-below-spec.csv" EXPORT_LAYER="-below-spec" \
              TYPE="CSV" SHAPE_TYPE="POINTS" \
              COORD_ORDER="Y_FIRST" EXPORT_ATTRS=NO

Cheers,
Bob