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QGIS strategy for denoting point feature changes over time?

My project file has a shapefile layer (point symbols) geolocating 50 historic street name mosaics embedded in concrete sidewalks throughout an urban neighborhood. Label for each point displays the historic street name. Contemporary street names and curb outlines are displayed on background shapefile layers from City GIS portal.

As sidewalks are gradually replaced, tiles at some locations will be removed, then reset at same locations in the new sidewalks. Tiles at some locations may never be removed, others may be removed/reset several times. Attribute table for my original shapefile includes separate columns for creation date and subsequent reset date.

How to indicate on map that a tile was present in original sidewalk, and now is reset in new walk, or even was reset several times? Label text needs to show historic street name.

My ideas:

  1. New shapefile layer with larger point symbol, e.g. a circle with no color fill. Circle symbol on new layer would surround but not obscure original symbol on original shapefile layer. New layer table includes only one attribute column = reset date. For tiles that are removed/reset several times, new shapefile layers can be added with bigger concentric circle symbols. Example, any mosaics that that are removed/reset 2 times would have a symbol on 3 separate layers (orig layer, reset #1 layer, reset #2 layer) and would display 2 concentric circles around the original symbol.
  2. Multiple, nested symbols, or label colors, or other differentiation on original layer. No clue how to place several different symbols on same layer. If this is a good strategy, please tell me what this process is called and point me to where to learn about it.
  3. Other strategy?
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I would recommend checking out rule based styling (e.g. here and here). Using rules you can setup various rule/expressions against the layer field(s) values to evaluate your various conditions. You may also stack rule symbols on-top of each other based on conditional priority using the Rendering order button. This may eliminate the step of having additional shps to track data change over time.

  • OK, thanks. I will check out rule based styling. End product is file(s) for submittal to City so they can add/update these features in City portal. – Benson Shaw May 11 '16 at 6:57

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