23/05/18

Permalink 10:58:42 am, by mholmes, 9 words, 12 views   English (CA)
Categories: Activity log; Mins. worked: 90

Submitted revised JADH article

Along with documentation of my responses to reviewer comments.

29/03/18

Permalink 03:49:00 pm, by mholmes, 43 words, 39 views   English (CA)
Categories: Activity log; Mins. worked: 75

Meeting re lot geometry overlap

Met with JSR, DBM and CB to discuss possible solutions to calculating the area of lot overlap. We've been hacking at this problem without a solution for some weeks, but it's possible that CB can implement something that will solve it for us.

21/03/18

Permalink 04:18:25 pm, by mholmes, 63 words, 44 views   English (CA)
Categories: Activity log; Mins. worked: 60

Fix for GeoJSON files with no coordinates

There's a persistent number of properties without coordinates, and in some cases an entire title has no properties with coordinates (usually where there's only one property on the title). This was generating invalid GeoJSON because it was unable to calculate an initial map view area. I've diagnosed and fixed that bug; the results are now showing up correctly in the Jenkins build products.

12/03/18

Permalink 02:17:10 pm, by mholmes, 10 words, 40 views   English (CA)
Categories: Activity log; Mins. worked: 90

Ethnicity assignments for new owners in Vancouver db

Ran the ethnicity process for all the new Kits owners.

Permalink 11:12:53 am, by mholmes, 46 words, 37 views   English (CA)
Categories: Activity log; Mins. worked: 120

Ethnicity assignments for new owners in Maple Ridge db

Adapted the code originally written to process the XML-from-MySQL to incorporate the more rigorous algorithm we refined when processing the directory material, then processed the remaining Maple Ridge owners to assign ethnicity. Only one marginal case, John William Kobata, who might be Japanese, Polish or Slovakian.

06/03/18

Permalink 04:56:06 pm, by mholmes, 70 words, 54 views   English (CA)
Categories: Activity log; Mins. worked: 120

Georeffed two more lots; updated docs; problem with next plan

Geo-reffed a couple more lots, this time in Maple Ridge, and in the process wrote new documentation for QGIS 3.0, in as much detail as possible. Then started on the next new plan, but it seems to be located rather in the wrong place, or there's somethingt very odd happening with it; it shows a street which doesn't exist where the plan should cover. Need to check back with the researcher.

05/03/18

Permalink 04:41:46 pm, by mholmes, 122 words, 47 views   English (CA)
Categories: Activity log; Mins. worked: 120

Final additions to the property plans: learning to GeoReference

Since the missing plans have now been retrieved from the LTO, I'm now taking AC's role to geo-reference the, I followed her excellent instructions, which unfortunately no longer match the version of QGIS that's current on my machine (I've moved from 2.18 to 3.0), so it took me a long time to figure out exactly what to do. I'll rewrite those instructions as a separate version in the same documentation file for version 3.0 when I've done a couple more. The main thing that took me AGES to realize was that to stop drawing a polygon and finalize it as a feature, you have to right-click. There's no GUI control at all, and no other way to do it as far as I can see.

09/02/18

Permalink 04:07:29 pm, by mholmes, 117 words, 73 views   English (CA)
Categories: Activity log; Mins. worked: 300

Polygons, JC properties, and other scripting

SR has offered to handle the polygon problem, so I generated for her a GeoJSON file containing all the features from the Maple Ridge db. I now have a library for doing that. KF needed a list of J-C owners and their properties as of 1942-03-04, so I've written and somewhat debugged that library (in XQuery); the results are odd, though, since they show no owners from Steveston or Salt Spring, so there needs to be further investigation there. Finally, one of our collaborators needs a hard copy of MP3 versions of our oral history wav files, so I resurrected my Python script and I'm running it now. It should be done by tonight or tomorrow.

30/01/18

Permalink 05:00:36 pm, by mholmes, 22 words, 66 views   English (CA)
Categories: Activity log; Mins. worked: 240

Still fighting with polygon intersection

Lots of attempts to use both turf and jsts to find intersection or union of polygons, all failing so far. Very frustrating.

29/01/18

Permalink 04:06:34 pm, by mholmes, 131 words, 74 views   English (CA)
Categories: Activity log; Mins. worked: 180

Some progress on area calculation

Finally figured out how to get area calculation working for polygons in OpenLayers, and I'll put it in here so I can find it the next time I'm pulling my hair out:

var wgs84Sphere = new ol.Sphere(6378137);
      
var getGeodesicArea = function(polygon) {
  var geom = (polygon.clone().transform('EPSG:3857', 'EPSG:4326'));
  var area = Math.abs(wgs84Sphere.geodesicArea(geom.getLinearRing(0).getCoordinates()));
  return area;
};

Pass a polygon geometry to the function and you'll get a value in m2. The magic number used to construct the sphere is the radius of the earth. abs is needed because the result is puzzlingly sometimes negative and sometimes positive; that doesn't seem to depend on the order of the coordinates, since my polygons are all properly wound. I can now go on to calculating intersection areas.

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