diff --git a/server/state.js b/server/state.js
index 1206769..defc7b6 100644
--- a/server/state.js
+++ b/server/state.js
@@ -35,6 +35,7 @@ function validateScene(s) {
     if (!Array.isArray(s[k])) throw new Error(`scene.${k} must be array`);
   }
   s.table = Object.assign({ width: 120, depth: 100, offsetX: 0, offsetZ: 0, show: true }, s.table || {});
+  s.ghostHeightCm = Number(s.ghostHeightCm || 4);   // minifigure-scale default
   s.paths = Array.isArray(s.paths) ? s.paths : [];
   for (const pth of s.paths) {
     if (!pth.id) throw new Error('path.id required');