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What is the best way to create polygons defining borders where aerial vintages change?

This is one big merge of aerial data here that needs to be split into 3 tiffs based on the vintages.

Doing it manually seems archaic, but if that is the best available, what is the correct editor tool(s) to use here? Snap to?

screenshot here

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  • What is a "merge" here? Sep 5, 2022 at 14:42

1 Answer 1

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I would recommend the Image Boundary plugin in QGIS. The documentation states that this has been replaced by the new Image Footprint plugin, however, I prefer to use the deprecated original. You will need to do the following to download the Image Boundary plugin:

Plugins > Manage and Install Plugins... > Settings > check "Show all deprecated plugins"

In this example, I used the plugin on 4 NAIP images. You can see from the screenshots that the plugin allows you to set either an extent boundary or valid pixels boundary. The resulting shapefile has very handy information in the attributes such as the raster name, path, proj4 string, spatial resolution, etc...

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  • Thanks for this 2 plugins... tried them both several times... best i could get is Image Footprint to create a polygon of the entire VRT aerial as shown here: i.imgur.com/5IWLLRs.png .... Seems like the VRT is a limitation perhaps? I would combine the tiffs but I get that "command line is too long" error... Is there a setting in either plugin I am not seeing that will create the additional polygons where the aerial vintages are clearly different? My original screenshot shows my beginning to manually drawing these needed polygons called GE_PARTS here : i.stack.imgur.com/fSntJ.jpg
    – sirgeo
    Nov 19, 2016 at 6:25
  • Ok, I see. Looks like you are trying to deconstruct an already mosaiced image. Is that correct? There is no way that I know to deconstruct an image like yours. It is best to create vector lines of each input image prior to running the mosaic so that you can use that to keep track of your vintages.
    – Aaron
    Nov 19, 2016 at 14:26
  • Yes, splitting (deconstructing) a mosaiced tiff from a grid shp based on an AOI is objective. Grid is not based on vintages. Image Footprint does get us an outline shp of the whole mosaic which is helpful. What editor tools are best for manually creating the vintage polygons (GE_Parts)? Will be starting / editing the new outline shp of whole mosaic from Image Footprint's output. Would it be better to create just one polygon shp with multiple vintage areas (3 columns (records) in this case) or create 3 separate polygon shp? Also, which "clip raster using polygon" tool is best for this?
    – sirgeo
    Nov 19, 2016 at 15:54
  • Using QGIS > Raster > Extraction > Clipper seems to only work when vintages are separated into 3 individual polygon shps... spent many hours today trying to implement 1 shp (3 records), but it kept throwing up the "self-intersecting" errors even after checking 10+ times to make sure there were no "self-intersecting" issues... very aggravating the way these type of problems keep popping up.. e.g. the "SAGA cannot do multibands" error; why does it allow the SAGA tool to be implemented and all its requirements filled in only to throw up errors at the last step? argh! QGIS can do better than this.
    – sirgeo
    Nov 20, 2016 at 6:04
  • ArcGIS has a Create Fishnet tool that will create a vector tile map with user specified origin and tile sizes. The tiles could then be used to clip the raster. Does QGIS have anything similar?
    – Bjorn
    Jul 31, 2020 at 13:18

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