Area symbol editor uses minimum size with just one decimal place

[dl3sdo]

Actual behaviour

The area symbol editor uses just one decimal place for the 'Minimum size' in the 'Area settings' tab. The forest sample as well as drawing with the provided ISOM 2017-2 show (when using the 'Measure' tool) that the minimum size values use two decimal places, i.e., 2,25mm2 for symbol 406, etc.

Configuration

Mapper Version: v20200613.1 Operating System: Win7x64

[dg0yt]

I wonder if we shall just add another digit, or opt for rounding the limit. Such tiny objects seem to need human review anyway, no matter if 2.2 mm^2 or 2.3 mm^3.

[krticka]

This has high importance for automatic map checks. For example in OCAD there is Check legibility tool which checks minimum distances between objects, minimum line lenghts and area sizes. Than matters if area is 2,24 or 2,25 mm^2. Some mappers can produce map in Mapper, but in their contract they can have clause that the map will pass this Legibility check in OCAD. For example in Map Commission it is standard tool for checking the maps for IOF major events.

[dg0yt]

I hope objects which do not fail the automated check still receive the attention they need.

[lpechacek]

While the code change is trivial, I'm afraid the reasoning in the initial comment is flawed. The value 2.25 mm² is a result of map scaling. 1 mm² @ 1:15000 becomes 1.51.51 mm² @ 1:10000. The additional decimal place is a pure technicality. If I, for whatever reason, scale a map from 1:15000 to 1:13000, the said square millimeter on the map will become 1.331360947 mm². So the addition of just one additional decimal place in the map sample is just a coincidence, and depending on the initial minimum area value, digits on additional decimal places could have been generated.

Regarding the automated checks, I believe that the map legibility rules are defined by the limits of human vision and not computational peculiarities. Therefore specifying the legibility rules with 1/10 mm² resolution looks reasonable to me. Talking about the OCAD Legibility Check tool, I guess that the limits are hardcoded in the tool. I cannot tell for sure, however, as I have never seen the software live. When Mapper gets the legibility checks one day, I suggest that it works with the proposed resolution.

[dg0yt]

The additional decimal place is a pure technicality.

That's my point of view, too.

Looking for mm² minimum area sizes in the IOF PDFs yields:

• ISOM 2017-2 rev 2019:
  • 206 Gigantic boulder or rock pillar: Minimum area: 0.3 mm²
  • 307 Uncrossable marsh: Minimum area: 0.5 mm² (inside).
• ISSprOM 2019:
  • Minimum dimensions: Smallest area of colour Blue, green or yellow full colour: 0.5 mm² Black dot screen: 0.5 mm² Blue, brown, green or yellow dot screen: 1.0 mm²
  • 206 Gigantic boulder or rock pillar: Minimum area: 0.75 mm²
  • 213 Open sandy ground: Minimum area: 1 mm²
  • 214 Bare rock: Minimum area: 1 mm²
  • 301 Uncrossable body of water: Minimum area (inside): 0.5 mm²
  • 302 Crossable body of water: Minimum area (inside): 0.5 mm²
  • 401 Open land: Minimum area: 0.5 mm²
  • 402 Open land with scattered trees: Minimum area: 6.25 mm²
  • 403 Rough open land: Minimum area: 1 mm²
  • 404 Rough open land with scattered trees: Minimum area: 6.25 mm²
  • 405 Forest: Minimum area: 1 mm², in some cases 0.5 mm²
  • 406 Vegetation: slow running: Minimum area: 1 mm²
  • 408 Vegetation: walk: Minimum area: 0.5 mm²
  • 410 Impassable vegetation: Minimum area: 0.3 mm²
  • 412 Cultivated land: Minimum area: 9 mm²
  • 413 Orchard: Minimum area: 4 mm²
  • 414 Vineyard or similar: Minimum area: 4 mm²
  • 501.3 Paved area with scattered trees: Minimum area: 6.25 mm²
  • 520 Area that shall not be entered: Minimum area: 0.25 mm²
  • 521 Building: Minimum area: 0.25 mm²
  • 522 Canopy: Minimum area: 0.25 mm²
  • 709 Out-of-bounds area: Minimum area: 4 mm²
  • 714 Temporary construction or closed area: Minimum area: 0.25 mm²

Oh, I'm asked to discover 0.25 mm² out-of-bounds patches at competition speed.

[krticka]

There is nothing wrong with 0.25 mm² (4 sq. meters in real world on sprint map). Here is example of 520 Area that shall not be entered comparing to some other map symbols. Such small areas are typical for flower beds. Of course bounding line must be used to ensure legibility of such small patch.

[dg0yt]

Of course bounding line must be used to ensure legibility of such small patch.

Is the bounding line meant to be added strictly around the 0,25 mm², i.e. add to the footprint, or to be part of the 0.25 mm², i.e. cut from the key color?

[krticka]

The ISSprOM for 520 only says: The area shall always be delineated by a boundary line (at least 0.1 mm in width). For practical reasons (drawing with fill/create edge) bounding line is not strictly added around, but typically centred on the edge of 520 patch.

[dg0yt]

For practical reasons (drawing with fill/create edge) bounding line is not strictly added around, but typically centred on the edge of 520 patch.

Hm. This seems like another argument for not caring about the second place after the decimal point.

For practical reasons (import from OSM), I recently had to deal with a combined symbol (area + boundary line) where the boundary line was moved completed to the inner side area. I expect this to be used more often, and the "fill/create edge" tool may need to follow.

[krticka]

Hm. This seems like another argument for not caring about the second place after the decimal point.

In MC when deciding about minimum dimensions we are always discussing the influence of mandatory boundary lines (which are usually making patch more prominent). Such areas are often not drawn as combined symbol (boundary from several sides can be created by building, bank line, fence, etc.), measuring the area of stand-alone patch (without bounding line) I see as most practical.

For practical reasons (import from OSM), I recently had to deal with a combined symbol (area + boundary line) where the boundary line was moved completed to the inner side area. I expect this to be used more often, and the "fill/create edge" tool may need to follow.

Can you give me some example (data, graphic) of such situation? Thanks.

[lpechacek]

For practical reasons (import from OSM), I recently had to deal with a combined symbol (area + boundary line) where the boundary line was moved completed to the inner side area. I expect this to be used more often, and the "fill/create edge" tool may need to follow.`

Can you give me some example (data, graphic) of such situation? Thanks.

I think the illustration would be https://www.facebook.com/ollesmaps/posts/10160037235909676 and the associated defect report appears to be https://github.com/OpenOrienteering/mapper/issues/1602.