[求助AO开发高手]AO开发矢量转栅格中的问题

<P>在用到object.SetCellSize (envType [,cellSizeProvider] )时，不知道怎么确定cellSizeProvider的值，空值，NULL和省略，都会报错</P>
<P> </P>
如果不同的shapefile，他们合适的Cellsize是不一样的。现在我就想弄清楚，怎么给不同的矢量数据合适的Cellsize？

<P>看看下面的例子</P>
<P>http://arcscripts.esri.com/details.asp?dbid=13021</P>
<P>Summary
<P>This HSDensity V1.0 program developed by the Florida Marine Research Institute, will calculate the density for coverage and shapefile point, arc and polygon feature classes. This tool provides the capability to determine the distribution values over a surface. The magnitude at each sample location is distributed throughout a landscape, and a value is calculated for each cell in the output raster.

To install the ArcMap HSDensity application, please perform the following procedures:
1. On your PC you will need ArcGIS 8.3 or higher and SpatialAnalyst extension.
2. If you do not already have a directory on your PC called C:\Projects, then create one.
3. If you already have a called C:\Projects\HabitatStructure, then rename/delete the HabitatStructure directory.
4. Download, Copy and Unzip HSDensity.zip into C:\Projects. The unzip should create a directory called C:\Projects\HabitatStructure.
5. While in the C:\Projects\HabitatStructure\template directory, double left click on HSDensity.mxd.
6. HSDensity should now be active and ready for use.
7. You may find more instructions in C:\Projects\HabitatStructure\Doc\Readme html or doc files.

Regards,
carl.westergren@fwc.state.fl.us</P>


<P>http://arcscripts.esri.com/details.asp?dbid=12657</P>
<P>Form driven tool to convert the points of a DBF event theme to an ESRI GRID raster layer. Runs in ArcMap.

Using the extent of the event theme and the specified cell size the tool first generates an empty GRID. This GRID is then overlaid on the event point layer and values are assigned to each cell based on the characteristics of the point(s) that fall within each cell.

The tool is akin to the ArcInfo POINTGRID command except that this tool allows for specifying a rule to use in selecting a value for the cell when multiple points fall within it. Also, when Frequent Value is selected, it allows for specifying how to handle ties in frequency of values within cells.

There is no interpolation of the GRID among cells so cells in which no points fall are assigned NODATA or the specified NODATA value.

Due to constraints in ArcObjects is not currently possible to implement this tool on an event theme generated from a text file. This seems to be due to the fact that you cannot edit a text event theme in ArcMap. Within ArcMap it is easy to generate a DBF from your text or MS Excel would also work.

Choose your cell size wisely and be careful creating large GRIDS -- it will take some time.

ORIGINALLY UPLOADED 2/7/03

UPDATES:
2/14/03: Some users are reporting errors when using a large cell size. Somehow this is causing the selection set to fail. I am investigating as time permits and will post when fixed.

2/21/03: Uploaded updated code. Fixes bug requiring a specified value for frequency ties when this is not necessary. Also adds a status feature: the cell processing count is displayed in the form title as code runs. As yet still no fix for "large" cell sizes causing selection set failure.

-----------------------
Dan Rathert
GIS Programmer/Analyst
Resource Data Inc.
www.resdat.com
drathert@resdat.com
</P>

谢谢，总统。我先学习学习看，不会再来请教！

我看了，但是还不能解决我的问题