Author: Zhuotong Nan
Email: [email protected]
Date: Nov 21, 2007

ver: 1.0.0

Usage: GeneratePolygonsByPoints [data_file_name] {output shapefile name}
Rows*Cols (for ex, 260*250): (enter numbers of rows and cols for the source data file with
a format rows*cols. Incorrect input will stop the tool.)

data_file_name: source data file name; path can be included.
output shapefile name: optional, as its literal stated. path can be includes.

Supporting environment: Microsoft dotnet framework 2.0, ArcGIS 9.2 with dotnet assemblies, as
well as a valid ArcInfo license.

Remarks: Data file should be organized row by row (you should know exact row and column
number, which will be required to be entered after starting), starting from lower left corner.
In my initial case, the data file is generated by a modified Read_XMRG2 utility for XMRG
radar data file. The modified Read_XMRG2 will generate data with geographical coordinates
instead of HRAP coordinates as does original Read_XMRG2. Anyway, GeneratePolygonsByPoints
will also run against data file generated by original Read_XMRG2, however, with output
shapefile being in HRAP coordination.

Data file content looks like following:

-121.177570 37.897155 0.000000
-121.132468 37.907464 0.000000
-121.087345 37.917746 0.000000
-121.042201 37.928001 0.000000
-120.997037 37.938229 0.000000

The first column is longitude, second latitude, and the third precipitation value. The first
two columns represent that cells’ lower left coordinations. The first row indicates the lower
left cell; second is the next cell right to the first cell; after finishing a row, then begin
a row up the first row, and move upwards.

Output shapefile will be of geographic NAD83 datum. The first two columns will be converted
to points’ geographic location. Values (precp value in above example) will be lost. A new
field named "Index" will be generated to record this polygon’s lower left corner’s coordination
with a format of "lat_lon", for ex. 37.897155_-121.177570 for the first created cell. However,
you cannot depend on this field to link original source data file. In order to do link, you can
"ID" field in shapefile attribute table, which increases by one in consitence with source data
file.

As stated above, each cell is referred by its lower left corner’s coordination. The most upper
cells cannot be generated due to missing of necessary points (we only have lower edge’s
coord). Likewise, the most right cells are also missed.

The distribution also includes a test data file: xmrg0101199900z.out, with a 39*48 (rows*cols)
dimension.

For more information, please contact the author at [email protected].