---
title: "Body Map Viewer — Clarification Rounds"
description: "Q&A rounds on Jeroen's outline (T-1176 prep session): settled premises vs deferred workshop deliverables"
type: workshop
status: active
workshop: body-map-viewer
created: 2026-07-25
---

# Clarification Rounds (prep session)

Two AskUserQuestion rounds on [jeroen-outline.md](jeroen-outline.md), questions
merged from the lead and Tyre. Answers verbatim where they carry nuance.

## Settled by round A

1. **Zoom model — fully stepped.** *"fully stepped zoom, but still cursor centers
   and the edge scrolling also works. Just, we click through the zoom levels on
   scroll. We could investigate a client side morph."* Scroll wheel steps through
   discrete zoom levels; cursor-anchored centering and edge-scroll pan are retained;
   a client-side morph/tween between levels is an investigation item. **Supersedes**
   the continuous-multiplier zoom of the T-1143 ruling (entry-seam ruling 3) — to be
   recorded as a deliberate revision when the workshop's decisions are filed.
2. **Vocabulary — "tile" repaired, "gridunit" coined.** Tile means the ground-level
   1×1 m unit (D-243) — Jeroen: *"I misused the term several times. Tile should mean
   the ground level 1x1m. I suggest we talk about gridunit (at zoom level) for the
   wrong uses."* Legitimate tile uses in the outline: the "~10px per tile" bottom-out
   (deepest step shows the 1 m tile at ~10 screen px on the smaller axis) and "the
   amount of steps … from largest to visible tile". Everything else (the n×n grid,
   per-pixel records) reads as **gridunits at a zoom level**.
3. **Data resolution is a tunable, not a constant.** *"I would like pixel resolution
   on the maps, but that may be too much, so maybe we do 5x5 pixels as a display
   unit … Crisper is better, but the computer must not catch fire."* Ideal = 1
   gridunit per screen pixel; acceptable fallback ≈ 1 gridunit per 5×5 px display
   unit (a 4K-class canvas drops from ~8.3M to ~330K gridunits). The knob is decided
   by measurement, not taste.
4. **Hydrology — deterministic equilibrium.** Lake fill, overflow re-routing,
   gorge carving are a single-pass settled end-state computed from heightmap +
   moisture/climate as a pure function of seed ("over time" = geological backstory).
   Extends today's D8 drainage; no stateful simulation.

## Confirmed inline

- **Step boundaries = compute-chunk boundaries.** Tyre's reading that zoom-step
  boundaries and deterministic-generation load-partitioning boundaries are intended
  to be the same boundaries stands unchallenged.
- **Server side is in play** (premise from the outline itself): content
  determination relocates to the server; the server sends what is at a given
  world coordinate at that zoom level. Dudley is core roster.
- **Performance is a first-class driver** (lazy/late compute, TTL cache,
  "snappy after first calc").

## Deferred to the workshop (round B — all four explicitly "workshop deliverable")

1. **Named-feature encoding** (rivers/settlements/roads/POIs: dense rasters +
   sparse feature list vs inline identity vs ids-with-lookup). Jeroen's constraint:
   *"best fidelity vs wire contract possible … The information the client needs
   needs to be there."*
2. **Data-canvas sizing** (canonical fixed size for all clients vs viewport-sized
   capped): *"I see value in both."*
3. **Cache-tier architecture** (server TTL / client layer cache / disk-persisted
   global tier / predictive precache — which exist, and what "always keep the
   global level" means concretely).
4. **Map time axis** (climatology vs current sim state for frozen/flooded).
   Jeroen's hint, on record as direction not ruling: *"maybe we put shorter ttl on
   the climate sim state components?"*
5. **Step count** largest→visible-tile (deferred in the outline itself), coupled to
   compute-chunk partitioning.

## Flags carried forward (not questions)

- **Cliff/multi-height data model gap** (Tyre): "two heights in the same tile and
  cliff forming" exceeds the one-height-per-cell model (`elev_q` u8); the per-
  gridunit payload needs a sub-unit vertical-structure answer, and a ruling on
  whether cliffs are Phase-4 Atlas content or Phase-5 geometry.
- **Phase-5 reuse** of the map drawing component (same code path as the future
  in-world viewport or Atlas-only) — scoping decision for the workshop.