Vector tiles: increase the size of the envelope used to clip geometries #79030

iverase · 2021-10-13T05:47:30Z

While testing we realise we have some visual artefacts when displaying big polygons. These artefacts are noticed because you can see the edges of the tiles, for example:

This is due to the size of the clipping envelope that is not big enough. Therefore we propose to increase from 1 pixel precision to 10 pixel precision. After this change the artefacts are gone:

elasticmachine · 2021-10-13T05:47:33Z

Pinging @elastic/es-analytics-geo (Team:Analytics)

iverase · 2021-10-13T07:35:18Z

@elasticmachine run elasticsearch-ci/packaging-tests-windows-sample

iverase · 2021-10-13T15:35:06Z

@elasticmachine run elasticsearch-ci/packaging-tests-windows-sample

imotov · 2021-10-13T18:25:36Z

...gin/vector-tile/src/main/java/org/elasticsearch/xpack/vectortile/feature/FeatureFactory.java

@@ -62,7 +62,8 @@ public FeatureFactory(int z, int x, int y, int extent) {
        final Rectangle r = SphericalMercatorUtils.recToSphericalMercator(GeoTileUtils.toBoundingBox(x, y, z));
        final Envelope tileEnvelope = new Envelope(r.getMinX(), r.getMaxX(), r.getMinY(), r.getMaxY());
        final Envelope clipEnvelope = new Envelope(tileEnvelope);
-        clipEnvelope.expandBy(this.pixelPrecision, this.pixelPrecision);
+        // expand enough the clip envelope to prevent visual artefacts
+        clipEnvelope.expandBy(10 * this.pixelPrecision, 10 * this.pixelPrecision);


Not sure I quite understand where this 10 is coming from?

That is a good point as it was mainly experimental. A quick search got me this info: https://blog.cyclemap.link/2020-01-25-tilebuffer/

In this blog, it is recommended depending on the zoom:

zoom Cell buffer size (pixels)

< 15 extent / 64

15..17 extent / 32

> 17 extent / 16

Much bigger than what I am proposing. Maybe @thomasneirynck can give a suggestion here?

@iverase

from the blog you linked, it seems to be focused on rendering the tiles to rasters client-side.

I'd like to try it out in Kibana Maps, but 90% sure we would not be running into these "line-connection" artifacts with mapbox with a small buffer. Fwiw - these artifacts from the blog arise due to line-connections, so we should try with a line dataset.

The main desired outcome (from kibana-maps perspective) is that the tile-outline is omitted from the actual tile-contents (since they would have negative tile-coords). Which seems to be the case with this PR.

Perhaps @jsanz @nickpeihl can weigh in: are we applying a similar buffer when generating the EMS tiles? if so, how large?

Every layer on the basemap has its own buffer size that is used to compute the final tile buffer used by the PostGIS ST_AsMVTGeom function, based also on the zoom level as you can see in this line.

tile_buffer_size = int(self.extent * layer.buffer_size / self.pixel_width)

The most common buffer size for the basemap layers is 4 but for point layers like points of interest or place names, the buffer is bigger, I understand to get the labels properly rendered.

Buffer sizes

Thanks @thomasneirynck and @jsanz!

I am not sure I understand the formula above. For the discussion here it seems that the buffer size in that case is expressed in different system and pixel_width is used to transform between both systems (It does not seem to be dependent on zoom level).

I agree that what we want is to remove the tile outline by having negative coordinates on the polygons that cross the tile. I checked with line geometries and they are not affected.

Therefore my proposal is to set a default buffer size of 5 pixels and later on we can expose this parameter so users can have control over it. Any thoughts?

imotov

Could you add a comment in the code with TODO list explaining our thinking here and how we came up with this magic number. It might be also good to pull it out as a constant.

iverase · 2021-10-18T07:39:53Z

I created a static variable to hold the default buffer size in pixels and added a TODO.

imotov

LGTM

…es (elastic#79030) Removes the tile outline from polygons that cross contiguous tiles.

elasticsearchmachine · 2021-10-19T05:14:30Z

💚 Backport successful

Status	Branch	Result
✅	7.x
✅	7.15

…es (elastic#79030) Removes the tile outline from polygons that cross contiguous tiles.

…es (#79030) (#79417) Removes the tile outline from polygons that cross contiguous tiles.

…es (#79030) (#79416) Removes the tile outline from polygons that cross contiguous tiles.

* upstream/master: (34 commits) Add extensionName() to security extension (elastic#79329) More robust and consistent allowAll indicesAccessControl (elastic#79415) Fix circuit breaker leak in MultiTerms aggregation (elastic#79362) guard geoline aggregation from parents aggegator that emit empty buckets (elastic#79129) Vector tiles: increase the size of the envelope used to clip geometries (elastic#79030) Revert "[ML] Add queue_capacity setting to start deployment API (elastic#79369)" (elastic#79374) Convert token service license object to LicensedFeature (elastic#79284) [TEST] Fix ShardPathTests for MDP (elastic#79393) Fix fleet search API with no checkpints (elastic#79400) Reduce BWC version for transient settings (elastic#79396) EQL: Rename a test class for eclipse (elastic#79254) Use search_coordination threadpool in field caps (elastic#79378) Use query param instead of a system property for opting in for new cluster health response code (elastic#79351) Add new kNN search endpoint (elastic#79013) Disable BWC tests Convert auditing license object to LicensedFeature (elastic#79280) Update BWC versions after backport of elastic#78551 Enable InstantiatingObjectParser to pass context as a first argument (elastic#79206) Move xcontent filtering tests (elastic#79298) Update links to Fleet/Agent docs (elastic#79303) ...

Vector tiles: increase the size of the envelope used to clip geometries

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iverase added >non-issue :Analytics/Geo Indexing, search aggregations of geo points and shapes v8.0.0 v7.16.0 labels Oct 13, 2021

iverase requested a review from imotov October 13, 2021 05:47

elasticmachine added the Team:Analytics Meta label for analytical engine team (ESQL/Aggs/Geo) label Oct 13, 2021

imotov reviewed Oct 13, 2021

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iverase added 2 commits October 15, 2021 14:54

Merge branch 'master' into clipEnvelope

9c5da4f

Change buffer size to 5 pixels

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imotov reviewed Oct 15, 2021

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iverase added 3 commits October 16, 2021 08:48

Add TODO and explanation of the value

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Merge branch 'master' into clipEnvelope

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spotless

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imotov approved these changes Oct 18, 2021

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iverase added the v7.15.2 label Oct 19, 2021

iverase merged commit 7ad1424 into elastic:master Oct 19, 2021

iverase deleted the clipEnvelope branch October 19, 2021 05:12

iverase added the auto-backport-and-merge label Oct 19, 2021

iverase mentioned this pull request Oct 19, 2021

[7.x] Vector tiles: increase the size of the envelope used to clip geometries (#79030) #79416

Merged

iverase added a commit to iverase/elasticsearch that referenced this pull request Oct 19, 2021

Vector tiles: increase the size of the envelope used to clip geometri…

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…es (elastic#79030) Removes the tile outline from polygons that cross contiguous tiles.

iverase mentioned this pull request Oct 19, 2021

[7.15] Vector tiles: increase the size of the envelope used to clip geometries (#79030) #79417

Merged

iverase added a commit to iverase/elasticsearch that referenced this pull request Oct 19, 2021

Vector tiles: increase the size of the envelope used to clip geometri…

d1281b7

…es (elastic#79030) Removes the tile outline from polygons that cross contiguous tiles.

elasticsearchmachine pushed a commit that referenced this pull request Oct 19, 2021

Vector tiles: increase the size of the envelope used to clip geometri…

ef6b6c8

…es (#79030) (#79417) Removes the tile outline from polygons that cross contiguous tiles.

elasticsearchmachine pushed a commit that referenced this pull request Oct 19, 2021

Vector tiles: increase the size of the envelope used to clip geometri…

e3c740c

…es (#79030) (#79416) Removes the tile outline from polygons that cross contiguous tiles.

jsanz mentioned this pull request Oct 19, 2021

[Maps] Use ES mvt elastic/kibana#114553

Merged

jakelandis added v8.0.0-beta1 and removed v8.0.0 labels Oct 27, 2021

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Vector tiles: increase the size of the envelope used to clip geometries #79030

Vector tiles: increase the size of the envelope used to clip geometries #79030

iverase commented Oct 13, 2021

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Vector tiles: increase the size of the envelope used to clip geometries #79030

Vector tiles: increase the size of the envelope used to clip geometries #79030

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💚 Backport successful

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