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Author Topic: Georeferencing Features  (Read 779 times)

PeterC

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Georeferencing Features
« on: 24 January 2018, 10:28:15 »
If you have a list of features (eg from The Journal or transcripts) within M4OPS that are not georeferenced, and have compiled them, then the next stage of the process is to georeference them. Essentially what you are doing is associating a geometry (a point, line or polygon) with each feature. M4OPS makes this easy for you.

Within your OPS in M4OPS:
  • For the Base layer select as large a scale map as possible (of around the best date), so your georeferencing can be as accurate as possible
    • You may also wish to select an overlay layer - and slide between the Base and Overlay - or remove the Overlay altogether (use the little 'x')
  • Move and zoom the map so you can see the places for the features you want to georeference
  • Under Advanced Options, click on the MFL tab
  • In the drop-down for Modifiable Feature Layers choose the All Features layer, and what should appear are
    • the points and polygons of the georeferenced features so far
      • [Note that if no features have so far been georeferenced, there will be one point showing named 'OPS - Centre', which is the centre of the OPS] - this point is there to show the layer exists, and can be deleted once you have started georeferencing]
    • a list of features still to be georeferenced
    • running totals of (georeferenced) features in the layer and features still to be georeferenced
    • [Note that the Base, Overlay and Feature sections disappear to allow more room for this process.]
  • Select the appropriate set of Fields from the drop-down (these are the predefined properties or values stored for each feature, including any optional ones) - NOT All Properties
  • Now to georeference each feature:
    • In the drop-down, select the feature still to be georeferenced
    • (If not already done so) select the Point, Line or Polygon button
    • You will notice that a blue dot appears under your arrow cursor, and this tells you that you place a point or vertex where you click
    • You will also notice some text appears near your cursor to remind you of the feature you are georeferencing
    • Create the geometry, ie:
      • for a point, click once on the map
      • for a line, click at least once on the map and then double-click for the last point
      • for a polygon, click at least twice on the map and then double-click for the last point
    • When a popup appears
      • in the drop-down confirm (or change) the feature you want to georeference
      • (if you had not already chosen a feature you can do so here)
      • click on Save
      • click on Close
    • [You will then notice that the feature appears on the map, and disappears from the list of features still to be georeferenced - the totals also change]
    • [If you click on Close without Saving the whole operation is cancelled]
  • At any time you can hover over georeferenced features to see their details
  • At any time you can move the positions of any of the points, or the vertices of polygons
    • Click on the Move button, and then drag the points to exactly where you want them
    • You can insert a vertex into any line (or polygon side) by clicking on the line and dragging
    • You can delete any line or polygon vertex just by clicking on it
  • At any time you can change the properties of any feature, delete it, or change its type of geometry (point, line, polygon)
    • click on the Alter button
    • click on the feature you want to change
    • if you want to delete the feature, click on the Delete button
    • otherwise, fill in the form - remembering to Save the form before you Close it
  • Periodically, and when you have finished, click on the (MFL) Save button on the left to save All Features in M4OPS (you can do this as many times as you want)
  • When finished click on the Close button, and the MFL will disappear
  • You can restart the process from the saved position at any time (but you may need to clear your browser's cache and reload M4OPS first for it to recognise your latest alterations)
Once the features are georeferenced please talk to Peter about downloading the Features files and recompiling your OPS within M4OPS.
« Last Edit: 26 April 2018, 10:51:55 by PeterC »

 

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