diff --git a/examples/basic/src/ClientMapRoutes.tsx b/examples/basic/src/ClientMapRoutes.tsx
index 0027555..9ecb4a1 100644
--- a/examples/basic/src/ClientMapRoutes.tsx
+++ b/examples/basic/src/ClientMapRoutes.tsx
@@ -34,6 +34,7 @@ const CameraRestrictionPage = lazy(() => import('./pages/map/camerarestriction/C
 const TiltPage = lazy(() => import('./pages/map/tilt/TiltPage').then(m => ({ default: m.TiltPage })));
 const UISettingsPage = lazy(() => import('./pages/map/uisettings/UISettingsPage').then(m => ({ default: m.UISettingsPage })));
 const VisibleRegionPage = lazy(() => import('./pages/map/visibleregion/VisibleRegionPage').then(m => ({ default: m.VisibleRegionPage })));
+const ProjectedCoordinatesPage = lazy(() => import('./pages/map/projected/ProjectedCoordinatesPage').then(m => ({ default: m.ProjectedCoordinatesPage })));
 const CameraSyncPage = lazy(() => import('./pages/map/camerasync/CameraSyncPage').then(m => ({ default: m.CameraSyncPage })));
 const MarkerLabelPositionPage = lazy(() => import('./pages/marker/labelposition/MarkerLabelPositionPage').then(m => ({ default: m.MarkerLabelPositionPage })));
 const MarkerAnimationPage = lazy(() => import('./pages/marker/animation/MarkerAnimationPage').then(m => ({ default: m.MarkerAnimationPage })));
@@ -91,6 +92,7 @@ function pageContent(page: string | undefined) {
     case 'tilt': return <TiltPage />;
     case 'ui-settings': return <UISettingsPage />;
     case 'visible-region': return <VisibleRegionPage />;
+    case 'projected-coordinates': return <ProjectedCoordinatesPage />;
     case 'camera-sync': return <CameraSyncPage />;
     case 'marker': return <MarkerIconsPage />;
     case 'marker-label-position': return <MarkerLabelPositionPage />;
diff --git a/examples/basic/src/pages/map/projected/ProjectedCoordinatesPage.tsx b/examples/basic/src/pages/map/projected/ProjectedCoordinatesPage.tsx
new file mode 100644
index 0000000..2a09123
--- /dev/null
+++ b/examples/basic/src/pages/map/projected/ProjectedCoordinatesPage.tsx
@@ -0,0 +1,183 @@
+import { useEffect, useState } from 'react';
+import {
+  ColorDefaultIcon,
+  MarkerAnimation,
+  Spherical,
+  createMarkerState,
+  type GeoPoint,
+  type MapCameraPosition,
+  type MapCoordinateSystem,
+  type MapDesignTypeInterface,
+  type MapViewHolder,
+  type MapViewStateInterface,
+  type MarkerState,
+} from '@mapconductor/js-sdk-core';
+import { Marker } from '@mapconductor/js-sdk-react';
+import { ControlPanel } from '../../../components/ControlPanel';
+import { MapViewContainer } from '../../../MapViewContainer';
+import { useSampleI18n } from '../../../samples/i18n';
+
+// android / ios の同ページと同じカメラ。並べて数値を突き合わせるため揃えてある。
+const INIT_CAMERA = { lat: 35.681236, lng: 139.767125, zoom: 12 };
+
+type Holder = MapViewHolder<unknown, unknown>;
+
+let dropCount = 0;
+
+/**
+ * タップした地点（赤）と、その投影座標を緯度経度へ戻した地点（青・小）に落とすマーカー。
+ *
+ * 投影と逆投影が合っていれば、青は赤のピン先に重なる。タップのたびに新しい id に
+ * するので、Drop がそのつど再生される。青は zIndex 1 にして、赤より手前に描く。
+ * 青は `iconSize` で小さくしている（android / ios の同ページと同じ）。
+ */
+function dropMarkers(tapped: GeoPoint, holder: Holder | null): MarkerState[] {
+  dropCount += 1;
+  const markers = [
+    createMarkerState({
+      id: `projected-tapped-${dropCount}`,
+      position: tapped,
+      icon: new ColorDefaultIcon({ fillColor: '#e53935', label: 'T' }),
+      animation: MarkerAnimation.Drop,
+    }),
+  ];
+  const projected = holder?.toProjectedPoint(tapped) ?? null;
+  const back = projected && holder ? holder.fromProjectedPoint(projected) : null;
+  if (back) {
+    markers.push(createMarkerState({
+      id: `projected-back-${dropCount}`,
+      position: back,
+      icon: new ColorDefaultIcon({ fillColor: '#1e88e5', label: 'P', iconSize: 28 }),
+      animation: MarkerAnimation.Drop,
+      zIndex: 1,
+    }));
+  }
+  return markers;
+}
+
+function formatSystem(system: MapCoordinateSystem): string {
+  return `${system.code ?? '(engine-defined)'} (${system.unit})`;
+}
+
+/**
+ * 1 地点ぶん: 緯度経度、投影座標（地図エンジンの座標系での x / y。画面座標ではない）、
+ * その x / y を緯度経度へ戻した値と元の地点とのずれ。ずれが 0 に近ければ往復できている。
+ */
+function ProjectionLines({ label, point, holder, unavailable }: {
+  label: string;
+  point: GeoPoint | null;
+  holder: Holder | null;
+  unavailable: string;
+}) {
+  const projected = point && holder ? holder.toProjectedPoint(point) : null;
+  const back = projected && holder ? holder.fromProjectedPoint(projected) : null;
+  const error = point && back ? Spherical.computeDistanceBetween(point, back) : null;
+  return (
+    <>
+      <p className="control-panel-note">{label}: {point?.toUrlValue(6) ?? unavailable}</p>
+      <p className="control-panel-note">
+        &nbsp;&nbsp;Projected: {projected ? `x=${projected.x.toFixed(2)}, y=${projected.y.toFixed(2)}` : unavailable}
+      </p>
+      <p className="control-panel-note">
+        &nbsp;&nbsp;Back: {back?.toUrlValue(6) ?? unavailable}{error !== null ? ` (error ${error.toFixed(3)} m)` : ''}
+      </p>
+    </>
+  );
+}
+
+function ProjectedCoordinatesContent({ holder, center, tapped }: {
+  holder: Holder | null;
+  center: GeoPoint | null;
+  tapped: GeoPoint | null;
+}) {
+  const { t } = useSampleI18n();
+  const unavailable = t({
+    en: 'Unavailable',
+    ja: '取得できません',
+    'es-419': 'No disponible',
+    de: 'Nicht verfügbar',
+    th: 'ไม่มีข้อมูล',
+    hi: 'उपलब्ध नहीं',
+  });
+
+  return (
+    <ControlPanel title={t({
+      en: 'Projected Coordinates',
+      ja: '投影座標',
+      'es-419': 'Coordenadas proyectadas',
+      de: 'Projizierte Koordinaten',
+      th: 'พิกัดที่ฉายแล้ว',
+      hi: 'प्रक्षेपित निर्देशांक',
+    })}>
+      <p className="control-panel-note">
+        {t({
+          en: 'Tap the map to project the tapped point.',
+          ja: '地図をタップすると、その地点の投影座標を表示します。',
+          'es-419': 'Toca el mapa para proyectar el punto tocado.',
+          de: 'Tippen Sie auf die Karte, um den angetippten Punkt zu projizieren.',
+          th: 'แตะแผนที่เพื่อฉายพิกัดของจุดที่แตะ',
+          hi: 'टैप किए गए बिंदु को प्रक्षेपित करने के लिए मैप पर टैप करें।',
+        })}
+      </p>
+      <p className="control-panel-note">
+        {t({
+          en: 'Markers: red T = tapped, blue P = back from the projected point.',
+          ja: 'マーカー: 赤の T がタップ地点、青の P が投影座標から戻した地点。',
+          'es-419': 'Marcadores: T rojo = punto tocado, P azul = de vuelta desde el punto proyectado.',
+          de: 'Marker: rotes T = angetippt, blaues P = aus dem projizierten Punkt zurückgerechnet.',
+          th: 'หมุด: T สีแดง = จุดที่แตะ, P สีน้ำเงิน = แปลงกลับจากพิกัดที่ฉาย',
+          hi: 'मार्कर: लाल T = टैप किया गया बिंदु, नीला P = प्रक्षेपित बिंदु से वापस बदला गया।',
+        })}
+      </p>
+      <p className="control-panel-note">
+        {t({ en: 'Coordinate system', ja: '座標系', 'es-419': 'Sistema de coordenadas', de: 'Koordinatensystem', th: 'ระบบพิกัด', hi: 'निर्देशांक प्रणाली' })}: {holder ? formatSystem(holder.coordinateSystem) : unavailable}
+      </p>
+      <ProjectionLines label={t({ en: 'Center', ja: '中心', 'es-419': 'Centro', de: 'Mittelpunkt', th: 'จุดกึ่งกลาง', hi: 'केंद्र' })} point={center} holder={holder} unavailable={unavailable} />
+      <ProjectionLines label={t({ en: 'Tapped', ja: 'タップ地点', 'es-419': 'Punto tocado', de: 'Angetippt', th: 'จุดที่แตะ', hi: 'टैप किया गया बिंदु' })} point={tapped} holder={holder} unavailable={unavailable} />
+    </ControlPanel>
+  );
+}
+
+export function ProjectedCoordinatesPage() {
+  const [state, setState] = useState<MapViewStateInterface<MapDesignTypeInterface<unknown>> | null>(null);
+  const [center, setCenter] = useState<GeoPoint | null>(null);
+  const [tapped, setTapped] = useState<GeoPoint | null>(null);
+  // ホルダは地図が出来てから付く。描画のたびに読むと、付いた後に描き直しが
+  // 起きず取り残されるので、地図の通知で取り直して state に持つ。
+  const [holder, setHolder] = useState<Holder | null>(null);
+  const [markers, setMarkers] = useState<MarkerState[]>([]);
+  // Some engines send no camera event when the map comes up: take the initial
+  // values from the state, retrying until the holder is attached.
+  useEffect(() => {
+    if (!state || holder) return;
+    const timer = window.setInterval(() => {
+      const attached = state.getMapViewHolder();
+      if (!attached) return;
+      setHolder(attached);
+      setCenter(current => current ?? state.cameraPosition.position);
+    }, 300);
+    return () => window.clearInterval(timer);
+  }, [state, holder]);
+  const refresh = (camera: MapCameraPosition) => {
+    setHolder(state?.getMapViewHolder() ?? null);
+    setCenter(camera.position);
+  };
+
+  return (
+    <MapViewContainer
+      initialCamera={INIT_CAMERA}
+      onStateReady={setState}
+      onCameraMove={refresh}
+      onCameraMoveEnd={refresh}
+      onMapClick={point => {
+        const current = state?.getMapViewHolder() ?? null;
+        setHolder(current);
+        setTapped(point);
+        setMarkers(dropMarkers(point, current));
+      }}
+    >
+      {markers.map(marker => <Marker key={marker.id} state={marker} />)}
+      <ProjectedCoordinatesContent holder={holder} center={center} tapped={tapped} />
+    </MapViewContainer>
+  );
+}
diff --git a/examples/basic/src/samples/documentation/index.ts b/examples/basic/src/samples/documentation/index.ts
index 880bf93..46625dd 100644
--- a/examples/basic/src/samples/documentation/index.ts
+++ b/examples/basic/src/samples/documentation/index.ts
@@ -14,6 +14,7 @@ import mapDesign from './pages/map-design';
 import flyTo from './pages/fly-to';
 import tilt from './pages/tilt';
 import visibleRegion from './pages/visible-region';
+import projectedCoordinates from './pages/projected-coordinates';
 import cameraSync from './pages/camera-sync';
 import marker from './pages/marker';
 import markerLabelPosition from './pages/marker-label-position';
@@ -56,6 +57,7 @@ const DOCUMENTATION: Record<string, SamplePageDoc> = {
   'fly-to': flyTo,
   tilt,
   'visible-region': visibleRegion,
+  'projected-coordinates': projectedCoordinates,
   'camera-sync': cameraSync,
   marker,
   'marker-label-position': markerLabelPosition,
diff --git a/examples/basic/src/samples/documentation/pages/projected-coordinates.ts b/examples/basic/src/samples/documentation/pages/projected-coordinates.ts
new file mode 100644
index 0000000..8aa90b3
--- /dev/null
+++ b/examples/basic/src/samples/documentation/pages/projected-coordinates.ts
@@ -0,0 +1,55 @@
+import type { SamplePageDoc } from '../types';
+
+const doc: SamplePageDoc = {
+  helpers: `function ProjectedValues({ holder, point }: { holder: MapViewHolder<unknown, unknown> | null; point: GeoPoint | null }) {
+  if (!holder || !point) return <p>Tap the map to project the tapped point.</p>;
+  const projected = holder.toProjectedPoint(point);
+  const back = projected ? holder.fromProjectedPoint(projected) : null;
+  return <pre>{JSON.stringify({
+    coordinateSystem: holder.coordinateSystem,
+    projected,
+    back: back?.toUrlValue(6),
+  }, null, 2)}</pre>;
+}`,
+  code: `<MapViewContainer
+  state={mapViewState}
+  onMapClick={point => setTapped(point)}
+/>
+
+<ProjectedValues holder={mapViewState.getMapViewHolder()} point={tapped} />`,
+  state: `const [tapped, setTapped] = useState<GeoPoint | null>(null);`,
+  explanation: {
+    en: [
+      'Convert between latitude/longitude and the coordinate system the map engine lays the map out in. These are not screen coordinates.',
+      'coordinateSystem tells which system the values are in, such as EPSG:3857 in meters. Engines that only have Mercator, and globe display, use EPSG:3857.',
+      'toProjectedPoint projects a point and fromProjectedPoint converts it back, so the round trip returns the original point.',
+    ],
+    ja: [
+      '緯度経度と、地図エンジンが地図を並べている座標系の値を相互に変換します。画面座標ではありません。',
+      'coordinateSystem は値がどの座標系か（EPSG:3857 のメートルなど）を示します。Mercator しか持たないエンジンと地球儀表示は EPSG:3857 です。',
+      'toProjectedPoint で投影し、fromProjectedPoint で戻すと元の地点に戻ります。',
+    ],
+    'es-419': [
+      'Convierte entre latitud/longitud y el sistema de coordenadas en que el motor dispone el mapa. No son coordenadas de pantalla.',
+      'coordinateSystem indica en qué sistema están los valores, por ejemplo EPSG:3857 en metros. Los motores solo Mercator y la vista de globo usan EPSG:3857.',
+      'toProjectedPoint proyecta un punto y fromProjectedPoint lo revierte, de modo que la ida y vuelta devuelve el punto original.',
+    ],
+    de: [
+      'Rechnet zwischen Breite/Länge und dem Koordinatensystem um, in dem die Karten-Engine die Karte anordnet. Das sind keine Bildschirmkoordinaten.',
+      'coordinateSystem gibt an, in welchem System die Werte liegen, etwa EPSG:3857 in Metern. Reine Mercator-Engines und die Globusansicht verwenden EPSG:3857.',
+      'toProjectedPoint projiziert einen Punkt, fromProjectedPoint rechnet ihn zurück; der Hin- und Rückweg ergibt wieder den ursprünglichen Punkt.',
+    ],
+    th: [
+      'แปลงระหว่างละติจูด/ลองจิจูด กับระบบพิกัดที่เอนจินแผนที่ใช้จัดวางแผนที่ ไม่ใช่พิกัดบนหน้าจอ',
+      'coordinateSystem บอกว่าค่าอยู่ในระบบใด เช่น EPSG:3857 หน่วยเมตร เอนจินที่มีแต่ Mercator และการแสดงแบบลูกโลกใช้ EPSG:3857',
+      'toProjectedPoint ฉายจุด และ fromProjectedPoint แปลงกลับ การแปลงไปกลับจึงได้จุดเดิม',
+    ],
+    hi: [
+      'अक्षांश/देशांतर और उस निर्देशांक प्रणाली के बीच रूपांतरण करें जिसमें मैप इंजन मैप को रखता है। ये स्क्रीन निर्देशांक नहीं हैं।',
+      'coordinateSystem बताता है कि मान किस प्रणाली में हैं, जैसे मीटर में EPSG:3857। केवल Mercator वाले इंजन और ग्लोब दृश्य EPSG:3857 का उपयोग करते हैं।',
+      'toProjectedPoint बिंदु को प्रक्षेपित करता है और fromProjectedPoint उसे वापस बदलता है, इसलिए आना-जाना मूल बिंदु लौटाता है।',
+    ],
+  },
+};
+
+export default doc;
diff --git a/examples/basic/src/samples/sampleIntro.ts b/examples/basic/src/samples/sampleIntro.ts
index b1f49e0..af4004c 100644
--- a/examples/basic/src/samples/sampleIntro.ts
+++ b/examples/basic/src/samples/sampleIntro.ts
@@ -73,6 +73,17 @@ const INTROS: Record<string, SampleIntro> = Object.fromEntries([
       hi: 'मैप को खिसकाने या ज़ूम करने पर दृश्य क्षेत्र अपडेट होता है।',
     },
   ),
+  intro(
+    'projected-coordinates',
+    {
+      en: 'Tap the map to see the tapped point in the map engine\'s coordinate system.',
+      ja: '地図をタップすると、その地点を地図エンジンの座標系で表示します。',
+      'es-419': 'Toca el mapa para ver el punto en el sistema de coordenadas del motor de mapas.',
+      de: 'Tippen Sie auf die Karte, um den Punkt im Koordinatensystem der Karten-Engine zu sehen.',
+      th: 'แตะแผนที่เพื่อดูจุดที่แตะในระบบพิกัดของเอนจินแผนที่',
+      hi: 'मैप पर टैप करें, टैप किया गया बिंदु मैप इंजन की निर्देशांक प्रणाली में दिखेगा।',
+    },
+  ),
   intro(
     'camera-sync',
     {
diff --git a/examples/basic/src/samples/sampleRegistry.ts b/examples/basic/src/samples/sampleRegistry.ts
index f6ef67d..0911a1b 100644
--- a/examples/basic/src/samples/sampleRegistry.ts
+++ b/examples/basic/src/samples/sampleRegistry.ts
@@ -25,6 +25,7 @@ export const SAMPLE_PAGES: SamplePageDefinition[] = [
   { id: 'tilt', label: { en: 'Tilt', ja: '傾き', 'es-419': 'Inclinación', de: 'Neigung', th: 'การเอียง', hi: 'झुकाव' }, group: 'Map', unavailableProviders: ['google-maps', 'mapkit'] },
   { id: 'ui-settings', label: { en: 'UI Settings', ja: 'UI設定', 'es-419': 'Ajustes de interfaz', de: 'UI-Einstellungen', th: 'การตั้งค่า UI', hi: 'UI सेटिंग' }, group: 'Map' },
   { id: 'visible-region', label: { en: 'Visible Region', ja: '表示領域', 'es-419': 'Región visible', de: 'Sichtbarer Bereich', th: 'พื้นที่ที่มองเห็น', hi: 'दृश्य क्षेत्र' }, group: 'Map' },
+  { id: 'projected-coordinates', label: { en: 'Projected Coordinates', ja: '投影座標', 'es-419': 'Coordenadas proyectadas', de: 'Projizierte Koordinaten', th: 'พิกัดที่ฉายแล้ว', hi: 'प्रक्षेपित निर्देशांक' }, group: 'Map' },
   { id: 'camera-sync', label: { en: 'Camera Sync', ja: 'カメラ同期', 'es-419': 'Sincronización de cámara', de: 'Kamerasynchronisation', th: 'การซิงก์กล้อง', hi: 'कैमरा सिंक' }, group: 'Map', showProviderSelector: false },
   { id: 'marker', label: { en: 'Marker Icons', ja: 'マーカーアイコン', 'es-419': 'Iconos de marcadores', de: 'Marker-Icons', th: 'ไอคอนมาร์กเกอร์', hi: 'मार्कर आइकन' }, group: 'Marker' },
   { id: 'marker-label-position', label: { en: 'Marker Label Position', ja: 'マーカーラベルの位置' }, group: 'Marker' },