Load Raster Data to a Field

A raster field is a column that allow a user to store raster objects in them. Rasters can be any imagery, jpg, pngs, etc...

To load data into the field you need to do the following:


///

/// Loads a raster into a raster field
///

/// feature where photo will be stored
/// image to be stored in record
/// Row of data to get the feature to store the raster dataset
/// Name of Raster field to save image to
public void LoadRasterDatasetToRasterField( IFeatureClass featureClass,
IRasterDataset rasterDataset, int OID, string RasterField )
{
try
{

//Get workspace for editing
IDataset dataset = (IDataset)featureClass;
IWorkspaceEdit workspaceEdit = (IWorkspaceEdit)dataset.Workspace;
workspaceEdit.StartEditing( false );
workspaceEdit.StartEditOperation();
IFeature feature = featureClass.GetFeature( OID );

//Find raster field index
int iRasterField = feature.Fields.FindField( RasterField );

//Create raster value with input raster dataset
IRasterValue rasterValue = new RasterValueClass();
rasterValue.RasterDataset = rasterDataset;

//Set raster value to the raster field
feature.set_Value( iRasterField, rasterValue );
feature.Store();

//Stop editing and save edits
workspaceEdit.StopEditOperation();
workspaceEdit.StopEditing( true );
}
catch (Exception ex)
{

MessageBox.Show( ex.Message );
}
}


This function basically starts an edit session to put data into the column. That means the featureclass be able to be edited.

Enjoy,

(I haven't forgot about Part 2 of my previous post, I've just been busy)

Generating Elevation Profile (Part 1)

Elevation Profiles are a nice was to see the topography over a given line. This can be used for planning things like roads, easiest routes of travel, etc...

In Part 1, I will discuss how to develop a Geoprocessing Script to publish to ArcGIS Server to get the elevation profile data. I will be using spatial analyst to extract and transform the data. Next I will take the values and write them to a csv, which will be returned to a user.

Let's get started:

1). Create a new model. Make sure spatial analyst is enabled.

2). Add Extract by Mask and Raster to Point tools from ArcToolbox

3). Create a feature set object and provide a polyline shapefile as the schema reference. Make the schema of the data as follows: OBJECTID, SHAPE, ELEVATION

Now that you have that, you model should look like this:

Now you need to create the script that will return a csv table to the user from your ArcGIS Server Service.

4). Create a new python file and call it GenerateCSV.py

5). Add the following Code:
# Import system modules
import arcgisscripting, os, sys


# Create the Geoprocessor object
gp = arcgisscripting.create()
gp.overwriteoutput = 1

InputPtFC = sys.argv[1]
pnt = gp.CreateObject("Point")
rows = gp.SearchCursor(InputPtFC)
filename = gp.scratchworkspace + os.sep + r"test.csv"

myfile = open(filename, 'w')
myfile.write("X,Y,ELEVATION" + "\n")
row = rows.next()
while row:
feat = row.shape
pnt = feat.GetPart()
myfile.write(str(pnt.x) + "," + str(pnt.y) + "," + str(row.getvalue("GRID_CODE")) + "\n")
row = rows.next()
myfile.close()
gp.Addmessage(filename + " Completed")
gp.setparameterastext(1, filename)


6). Save your file, open catalog -> add this script to your toolbox -> Input Parameters - Feature Class and Output Parameter - Table

7). Add the newly create script to your orginal model

8). Save the model

9). Publish to ArcGIS Server

The resulting model should look like this:

Enjoy

Long Running Scripts

Well, today I've hit a major road block, but I have a work around that should help many of you out there. Have you ever had a process that performs the same operation multiple times, but sometimes that operation fails. It's almost random. Take my situation, I have a clipping function that clips 100s of data sets, but it will randomly fail with a TopoEngine error. The help suggests that you check the geometries of your features, but it turns out, they are fine.

After much search, and questioning, I discovered that I need to delete the Geoprocessing object, then re-create it as such:


import arcgisscripting
from time import strftime
print str(strftime("%H:%M:%S"))
gp = arcgisscripting.create(9.3)
gp.overwriteoutput = True
print str(strftime("%H:%M:%S"))
del gp
print str(strftime("%H:%M:%S"))
gp = arcgisscripting.create(9.3)
gp.overwriteoutput = True
print str(strftime("%H:%M:%S"))


I did it twice, and measured the time. The first time you create the object, it will take the longest. On my machine, it takes 3 seconds to initialize, but after that, the process takes less than a second. Since the processes I am running already take 2-3 hours to complete a 1-2 minute increase is not too hard to live with.

I found that if I delete the geoprocessing object after I perform work on about 3 processes, I eliminate the error.

Enjoy

Listing Only Directories Using Python

Sometimes it's necessary to list directories, but when the os.listdir() method is called, the return list contains both folders and files. To fix this do the following:



dirs = [ name for name in os.listdir(--Directory--)) if os.path.isdir(os.path.join(str(--Directory--), name))]
for d in dirs:
d = str(d)
d = d.upper()
if d.find(".GDB") == -1:
outString = outString + str(d) + "; "



Methods like this are very helpful when you need to use tool validation. It allows you to quickly list all data in a directory, so users can select what they need.

You'll notice that the script has a find(). This is used because file geodatabases are essentially folders and therefore need to be excluded from the generated list.

Enjoy

Table to HTML table

Sometimes it's necessary to generate an html table for returned results. This tool basically takes any format that can support a search cursor, and generates an HTML file on your local disk. I was using this script in conjunction with some reporting tools to analyze AGS server logs.

Enjoy, and I hope it sparks some great GP ideas.



# ---------------------------------------------------------------------------
# TableToHtml.py
# ---------------------------------------------------------------------------

import sys, string, os, arcgisscripting
gp = arcgisscripting.create(9.3)

tablePath = gp.GetParameterAsText(0)
filePath = gp.GetParameterAsText(1)

outfile = open(filePath, "w")
fields = gp.ListFields(tablePath)

fieldNames = []
for field in fields:
if (field.type <> "Geometry" and field.type <> "BLOB"):
fieldNames.append(field.name)

outfile.write(" <table border=""1"">\n")

outfile.write(" <tbody><tr>\n")
for fieldName in fieldNames:
outfile.write(" <th>" + fieldName + "</th>\n")

outfile.write("</tr>\n")

cur = gp.SearchCursor(tablePath)
row = cur.Next()
while row:
outfile.write(" <tr>\n")
for fieldName in fieldNames:
outfile.write(" <td>" + str(row.getValue(fieldName)) + "</td>\n")

outfile.write("</tr>\n")

row = cur.Next()

del cur

outfile.write("</tbody></table>\n")

outfile.flush()
outfile.close()


ArcPad Tips and Thoughts

If anyone is developing for ArcPad 8.0, make sure you get service pack 1. This will correct a whole host of issues with the AXF files. Also, if you wish to connect to an AXF, here is an example:

dim objRSPS, pDS
Set objRSPS = Application.CreateAppObject("RecordSet")
Set pDS = Application.CreateAppObject("DataSource")
pDS.Open(pDSDataSource)
set objRSPS = pDS.OpenLayer("")
If objRSPS.RecordCount > 0 Then
objRSPS.MoveFirst
End If
...do other stuff...


So basically what is happening here, the objRSPS is creating a recordset object, then pDS is a data source object. pDS opens the data source via path name. objRSPS obtains the data set's records by referencing what layer you want from the axf database (axf is a compact sql server).

Note: the axf is picky, and it will tell you. If any domain values are invalid, it will catch it. So keep your databases clean if you are going to use this stuff.

Note 2: the shapefile is going away in arcpad, so get use to the AXF way of doing things.

Enjoy

Deprecation Plan for ArcGIS 9.3.1 and ArcGIS 9.4

The deprecation plans for ArcGIS 9.3.1 and ArcGIS 9.4 can be found here. It shows that VBA and VB6 are finally going away and there are OS support changes planned also. It's time for people to move on to new technologies, so start getting ready to transition now.