Map visual language · revision proposal

Two kinds of layer,
two ways to see.

Today the NWI wetlands, PAD protected areas, and flat-land slope overlays share a single quiet visual register — light hatch, low alpha, warm-grey wash. The user can't tell at a glance which polygons are warnings and which are opportunities. Three encodings below, each committing to a different way of separating the avoid set from the target set without breaking the existing 02_branding/01_map_visual_language.md taxonomy.

Avoid — hard exclusions

Legal/regulatory no-build areas. The user should perceive these as removed from the search space. NWI wetlands, PAD protected, Natura 2000.

Target — soft suitability

Continuous preference layers. The user should perceive these as where to look. Flat slope (<5%), and later irradiance, substation rings, etc.

01

Spotlight & Scrim

Dim the world so the target zones glow on their own.

A subtle 5–8% dark scrim drops across the entire viewport the moment a target layer is on. The slope_lt_5 polygon is a clip-path cutout — the basemap shines through at full brightness inside, dimmed outside.

Exclusion polygons get a much stronger version of the existing hatch: opacity ~38%, bolder slate stroke, animated march-ants outline on hover. They read as deliberately carved-out territory.

The eye naturally lands on the bright cutouts. Nothing changes about hue — only luminance, the channel the visual language doc reserves for soft constraints.

Trade-off Strongest at-a-glance "where to look" signal of the three. Subtle aesthetic change to the basemap (it dims when slope is on); designers occasionally find that surprising.
/preview/united-states/texas › Pecos County
Avoid · hard exclusion
Target · soft suitability
The target zone reads as light streaming in; the rest of the map politely steps back.
NWI · wetlandsSlate-blue horizontal hatch · 38% alpha
PAD · protectedNeutral slate diagonal hatch · 38% alpha
Slope · targetSpotlight cutout in viewport scrim
02

Halo & Aperture

No scrim. Strengthen the rim, let the boundary do the work.

Target zones gain a soft outward citron halo (8–12px feather) at low alpha — a positive, opt-in glow that doesn't add a new hue to the palette. Inside, the warm-grey wash is kept but the rim is now a 1.2px olive dashed stroke with a slow shimmer animation.

Exclusions get a thicker solid stroke (2px) and a per-polygon inner shadow, so they appear pressed into the page rather than painted onto it. The hatch stays at the current opacity range but reads as enclosed territory instead of a wash.

The most conservative direction — no global state, no basemap modification. Every change is per-polygon.

Trade-off Most reversible & least disruptive to the existing implementation. The "where to look" signal is weaker than spotlight; relies on the user noticing the rim treatment.
/preview/united-states/texas › Pecos County
Avoid · hard exclusion
Target · soft suitability
A rim of olive light around the target — the basemap is otherwise untouched.
NWI · wetlands2px slate-blue stroke · inner shadow
PAD · protected2px slate stroke · inner shadow
Slope · targetWarm-grey wash + outward citron halo
03

Topo Negative Space

Lift the avoid zones off the map. Engrave the target.

Most editorial direction. Inverts the brightness axis: exclusion zones are filled with near-paper (lighter than the basemap, not darker) and labelled with a small mono code-stamp — NWI, PAD. They read as "blanked off the chart" the way a USGS quad sheet clears city footprints.

The target zone is overlaid with a faint contour-line pattern in olive-mid, exactly the way topographic maps shade flat areas to invite the eye. The contour pattern becomes the layer's identity.

The strongest aesthetic break from the current map, but the one that reads most as "this is a survey-grade chart, not a consumer mood-board".

Trade-off Most distinctive identity; closest to USGS / IGM cartographic register. Requires per-polygon label placement to land; not all small NWI polygons can fit a stamp.
/preview/united-states/texas › Pecos County
Avoid · hard exclusion
Target · soft suitability
The map looks like it came out of a surveyor's drawer — which is the trust posture we actually want.
NWI · wetlandsLightened to paper · dashed slate-blue · stamp
PAD · protectedLightened to paper · dashed slate · stamp
Slope · targetOlive contour-line overlay · 1.2px olive rim
Recommendation

Ship Spotlight & Scrim, with two
concessions from the others.

Variant 01 (Spotlight) is the clearest "where to look" signal of the three. The luminance trick exploits the channel the visual-language doc already reserves for soft constraints — no new hue, no broken rules. The scrim is also opt-in by construction: it appears only when the user has toggled a target layer, so the default basemap stays untouched.

  1. Promote the role grouping into the legend. The constraint bar currently mixes avoid/target layers in one list. Split it into two labelled groups — Avoid · hard exclusion and Target · soft suitability — using the bordered chip style above. This single change does most of the cognitive work; the encoding refresh seals it.
  2. Bump exclusion opacity to ~38% & thicken the stroke. From variant 01. The current 25% slate hatch on a low-contrast stroke disappears against the basemap; the user can't see the warning.
  3. Keep the pressed-in inner shadow from variant 02. A small filter: inner-shadow on exclusion polygons adds physicality without consuming a hue. Cheap, reversible, subtle.
  4. Reserve variant 03 for the print/export view. The topo treatment looks superb on a static PDF page but is heavy at interactive zoom levels. Ship it later as the layout for /listing/:id/report.pdf.