I’ve found that sometimes I can not find the answer to a question until I know the answer & then it becomes ridiculously easy to find the answer.
One small annoying thing that I never spent much time was when you delete features from a feature class making it significantly smaller but the envelope does not get re-sized so the zoom extent (still the original extent) is too large. This often happens to use when we convert tables to an XY theme and there are blank records–most of our data shows in Minnesota but there are some in Oklahoma (I think). Once we eliminate or correct the blank records, our data view still pops out to include a large section of the United States even though we only have data in Minnesota.
A long, long time ago, Workstation ArcInfo had a simple command, Rebox, for just this purpose (actually it still does, I just don’t get to use it anymore)–it shrunk the extent to the smallest rectangle required to enclose all the data. Up until today, I thought the request for this feature was completely ignored.
While researching something else, I was digging around in the sde tables and found one, sde.sde_layers, that had the interesting fields, minx, miny, maxx, and maxy. My quick & dangerous test (I performed it on a throw-away feature class in a throw-away geodatabase) gave me the results I wanted–once I loaded the feature class into ArcMap, the extent was a nice, tight rectangle around my features.
Is this a supported way to Rebox the extent? No.
Is it recommend by ESRI or me? No.
Will it screw up your entire geodatabase, making you lose all your data & costing you your job? Probably not but do you want to take that chance?
Will it get the job done? Maybe. But in the process of writing this post, I found two safer ways to go about it. First, the straight-forward, sde command-line way that probably always existed that I never found until today, sdelayer -o alter had an -E option to reset the extent, including the ability to either specify it or have sde calculate it. Ok, that is usable for one person in our organization.
Previously, we had found either a VBA or other tool for doing this but had minimal success with it. Today, I found an ArcGIS 10 Add-In that is suppose to do the same thing. In my experiments (sample size n=1) it worked perfectly. If you need this sort of functionality, I would recommend trying out this Add-In first, if that fails go the sde command line route. Use the direct SQL method at your own risk!
I achieved the resetting of the extent with the following VB code which is executed by an on click event of a button in ArcCatalog:
Try
Dim pGXApplication As IGxApplication
pGXApplication = My.ArcCatalog.ThisApplication
Dim pGxObject As IGxObject
pGxObject = pGXApplication.SelectedObject
If Not TypeOf pGxObject.InternalObjectName Is IFeatureClassName Then
Exit Sub
End If
Dim pName As IName
pName = pGxObject.InternalObjectName
‘ Get Extent of dataset
Dim pGeoDataset As IGeoDataset
pGeoDataset = pName.Open
Dim pEnvelope As IEnvelope
pEnvelope = pGeoDataset.Extent
Dim pArea As IArea
pArea = pEnvelope
Dim d As Double
d = pArea.Area
Dim pFeatureClassManage As IFeatureClassManage
If pGxObject.Category = “Shapefile” Then
pFeatureClassManage = pName.Open
Else
Dim pSchemaLock As ISchemaLock
pSchemaLock = pName.Open
pSchemaLock.ChangeSchemaLock(esriSchemaLock.esriExclusiveSchemaLock)
pFeatureClassManage = pSchemaLock
End If
pFeatureClassManage.UpdateExtent()
pGeoDataset = pName.Open
pEnvelope = pGeoDataset.Extent
pArea = pEnvelope
Dim d2 As Double
d2 = pArea.Area
MsgBox(“The area for ” & pGxObject.Name.ToString & vbCr & “was ” + d.ToString & vbCr & “and is now ” & d2.ToString, MsgBoxStyle.Information, “Successfully updated spatial extent”)
Catch ex As System.Exception
MsgBox(ex.Message)
End Try