Creating Filters

To search or view specific information on an overlay, use property filters or feature filters in GeognoSIS.

Filters can be used in overlay scans and spatial searches.

This example shows you how to create a property filter that allows only Building Out-line items to be selected from an Open Closest Item search within a Landline dataset.

' Create a Building Only property filter:
oSis.CreatePropertyFilter("BuildingsOnly", "_DESC$=""Building Outline"""
' Open the nearest item to the click position:
oSis.OpenClosestItem(v.x, v.y, v.z, r, "H", "BuildingsOnly")

This example shows you how to create a feature filter which allows only Building Outlines, Bench Marks, Water Features and Building seeds to be shown on a Landline overlay. Once set, the filter remains in force for all images.

' Create a feature filter:
oSis.CreateFeatureFilter("ofltPermittedLandline", "Land-Line")
' Hides all features.
oSis.ChangeFeatureFilter("ofltPermittedLandline", 0, 0 + 2)
' allows Building Outlines.
oSis.ChangeFeatureFilter("ofltPermittedLandline", 1, 1)
' allows Bench Mark.
oSis.ChangeFeatureFilter("ofltPermittedLandline", 26, 1)
' allows Water Features.
oSis.ChangeFeatureFilter("ofltPermittedLandline", 59, 1)
' allows Building Seeds.
oSis.ChangeFeatureFilter("ofltPermittedLandline", 321, 1)
' sets the filter onto the first overlay.
oSis.SetOverlayFilter(0, "ofltPermittedLandline")