CSV Grid Files Guidelines and Restrictions

Before importing CSV Grid files, consider the following guidelines and restrictions:

•          The CSV file should not use SQL reserved words as field names. For example field names should not contain: "merge", "load", "add", etc. Here is the full list of SQL reserved words: http://technet.microsoft.com/en-us/library/ms189822.aspx  

•          Make sure that an XML header file exists for each CSV file. The header information, as shown in the following example, defines the properties of the raster image, such as the cell size, and the reference point location of the Grid cell. Click here for a table describing the XML header file fields.

<GridHeader>

<CellSize>0.01</CellSize>

<CellReference>Center</CellReference>

</GridHeader>

•          Make sure that the CSV file is correctly formatted and that the latitude and longitude coordinates are in decimal degrees (DD) format, using positive or negative values. If the coordinates are in units such as degree/minute/second or degree/decimal/minute, you must first convert them to decimal degrees (+/- DD). For information about converting coordinates, go to the Directions Magazine web site: http://www.directionsmag.com/site/latlong-converter.

•       For North American data, if the latitude and longitude values in the CSV file are based on North American datums NAD83 or NAD27, make sure that you project them again, transforming the values to Geographic Coordinate Systems GCS_WGS_1984, Datum D_WG.

•          Make sure that the CSV Grid file has a valid geometry. A valid geometry consists of points that are aligned to the same grid. The latitude and longitude values must be an exact multiple of the cell size from the lower left cell in the grid. If the file contains a row or rows with values that do not align with the grid, Touchstone will round the values to the nearest exact multiple.

•          Touchstone supports up to 65 million grids per file.

•          If you plan to import a CSV Grid file with a predefined legend, make sure that you select a Legend field that has the same data type or a compatible data type, and that contains the same range of values as the field in the original file used to generate the predefined legend.

•          Make sure that there are no duplicate points that share the same latitude and longitude. You can identify duplicate records using SQL, SPSS, or ArcMap tools. Duplicate records will cause the import to fail.