> ## Documentation Index
> Fetch the complete documentation index at: https://mintlify.com/thareUSGS/GDAL_scripts/llms.txt
> Use this file to discover all available pages before exploring further.

# Web Mapping Tools

> Examples for accessing USGS Astrogeology WMS services with GDAL, OpenLayers, and Leaflet

## Overview

The USGS Astrogeology Science Center provides Web Map Service (WMS) endpoints for planetary data. This guide demonstrates how to access these services using GDAL configuration files and web mapping libraries.

## GDAL WMS Configuration

### Overview

GDAL can retrieve images from WMS layers using XML configuration files, enabling command-line access to planetary base maps and elevation data.

### Basic Usage

```bash theme={null}
gdal_translate -of PNG gdal_MDIM21.xml mdim21_out.png
```

This command retrieves data from a WMS layer and exports it as a PNG image.

## WMS Configuration Files

### Mars MDIM 2.1 Mosaic

Access the Mars Digital Image Mosaic (MDIM 2.1):

```xml theme={null}
<GDAL_WMS>
  <Service name="WMS">
    <Version>1.1.1</Version>
    <ServerUrl>http://planetarymaps.usgs.gov/cgi-bin/mapserv?map=/maps/mars/mars_simp_cyl.map</ServerUrl>
    <SRS>EPSG:4326</SRS>
    <ImageFormat>image/jpeg</ImageFormat>
    <Layers>MDIM21</Layers>
  </Service>
  <DataWindow>
    <UpperLeftX>280</UpperLeftX>
    <UpperLeftY>45</UpperLeftY>
    <LowerRightX>290</LowerRightX>
    <LowerRightY>35</LowerRightY>
    <SizeX>1000</SizeX>
    <SizeY>1000</SizeY>
  </DataWindow>
  <Projection>EPSG:4326</Projection>
  <BandsCount>3</BandsCount>
  <DataType>Byte</DataType>
</GDAL_WMS>
```

**Key Parameters:**

* **ServerUrl**: WMS endpoint URL
* **Layers**: Layer name (MDIM21)
* **ImageFormat**: `image/jpeg` for RGB imagery
* **BandsCount**: 3 (RGB)
* **DataType**: Byte (8-bit)

### Mars MOLA Elevation

Access Mars Orbiter Laser Altimeter (MOLA) elevation data:

```xml theme={null}
<GDAL_WMS>
  <Service name="WMS">
    <Version>1.1.1</Version>
    <ServerUrl>http://wms.wr.usgs.gov/cgi-bin/mapserv?map=/maps/mars/mars_simp_cyl_elev.map</ServerUrl>
    <SRS>EPSG:4326</SRS>
    <ImageFormat>image/tiff</ImageFormat>
    <Layers>MOLA_elev</Layers>
  </Service>
  <DataWindow>
    <UpperLeftX>280</UpperLeftX>
    <UpperLeftY>45</UpperLeftY>
    <LowerRightX>290</LowerRightX>
    <LowerRightY>35</LowerRightY>
    <SizeX>1000</SizeX>
    <SizeY>1000</SizeY>
  </DataWindow>
  <Projection>EPSG:4326</Projection>
  <BandsCount>1</BandsCount>
  <DataType>Int16</DataType>
</GDAL_WMS>
```

**Key Parameters:**

* **ImageFormat**: `image/tiff` for elevation data
* **BandsCount**: 1 (elevation only)
* **DataType**: Int16 (16-bit signed integer)

### Moon LOLA Elevation

Access Lunar Orbiter Laser Altimeter (LOLA) elevation data:

```xml theme={null}
<GDAL_WMS>
  <Service name="WMS">
    <Version>1.1.1</Version>
    <ServerUrl>http://wms.wr.usgs.gov/cgi-bin/mapserv?map=/maps/earth/moon_simp_cyl_elev.map</ServerUrl>
    <SRS>EPSG:4326</SRS>
    <ImageFormat>image/tiff</ImageFormat>
    <Layers>LOLA_elev</Layers>
  </Service>
  <DataWindow>
    <UpperLeftX>175</UpperLeftX>
    <UpperLeftY>45</UpperLeftY>
    <LowerRightX>185</LowerRightX>
    <LowerRightY>35</LowerRightY>
    <SizeX>1000</SizeX>
    <SizeY>1000</SizeY>
  </DataWindow>
  <Projection>EPSG:4326</Projection>
  <BandsCount>1</BandsCount>
  <DataType>Int16</DataType>
</GDAL_WMS>
```

## GDAL WMS Usage Examples

### Export Specific Region

Create a configuration file with your desired extent:

```xml theme={null}
<DataWindow>
  <UpperLeftX>-180</UpperLeftX>   <!-- West longitude -->
  <UpperLeftY>90</UpperLeftY>      <!-- North latitude -->
  <LowerRightX>180</LowerRightX>   <!-- East longitude -->
  <LowerRightY>-90</LowerRightY>   <!-- South latitude -->
  <SizeX>3600</SizeX>              <!-- Output width in pixels -->
  <SizeY>1800</SizeY>              <!-- Output height in pixels -->
</DataWindow>
```

Then export:

```bash theme={null}
gdal_translate -of GTiff mars_config.xml mars_region.tif
```

### Get Dataset Information

```bash theme={null}
gdalinfo gdal_mars_MOLA_elev.xml
```

Output shows:

* Coordinate system
* Pixel size
* Bounding box
* Data type
* Band information

### Reproject WMS Data

```bash theme={null}
gdalwarp -t_srs "+proj=sinu +lon_0=0 +x_0=0 +y_0=0 +R=3396190 +units=m" \
  gdal_mars_MOLA_elev.xml mars_sinusoidal.tif
```

### Create Hillshade from Elevation WMS

```bash theme={null}
# Download elevation data
gdal_translate -of GTiff gdal_mars_MOLA_elev.xml mars_elev.tif

# Generate hillshade
gdaldem hillshade mars_elev.tif mars_hillshade.tif -z 5 -az 315 -alt 45
```

## OpenLayers Example

### Interactive Moon Map

HTML template for displaying lunar WMS layers with OpenLayers:

```html theme={null}
<!DOCTYPE html>
<html>
<head>
  <link rel="stylesheet" href="http://astrowebmaps.wr.usgs.gov/webmapatlas/styles/ol.css" />
  <script src="http://astrowebmaps.wr.usgs.gov/webmapatlas/ol/OpenLayers-2.10/OpenLayers.js"></script>
  <style>
    #map { width: 100%; height: 100%; border: 1px solid black; }
  </style>
</head>
<body>
  <div id='map'></div>
  <script type="text/javascript">
    var map = new OpenLayers.Map('map', { 
      maxExtent: new OpenLayers.Bounds(0, -90, 360, 90) 
    });
    
    var wmsURL = [
      "http://planetarymaps.usgs.gov/cgi-bin/mapserv?map=/maps/earth/moon_simp_cyl.map"
    ];

    // Add LOLA Color layer
    var LOLA_color = new OpenLayers.Layer.WMS(
      'LOLA Color',
      wmsURL,
      { layers: 'LOLA_color', format: 'image/jpeg' },
      { wrapDateLine: true, buffer: 1, isBaseLayer: true, visibility: true }
    );
    map.addLayer(LOLA_color);

    // Add LOLA Steel layer
    var LOLA_steel = new OpenLayers.Layer.WMS(
      'LOLA Steel',
      wmsURL,
      { layers: 'LOLA_steel', format: 'image/jpeg' },
      { wrapDateLine: true, buffer: 1, isBaseLayer: true, visibility: false }
    );
    map.addLayer(LOLA_steel);

    // Add LOLA Black & White layer
    var LOLA_bw = new OpenLayers.Layer.WMS(
      'LOLA B&W',
      wmsURL,
      { layers: 'LOLA_bw', format: 'image/jpeg' },
      { wrapDateLine: true, buffer: 1, isBaseLayer: true, visibility: false }
    );
    map.addLayer(LOLA_bw);

    // Set initial view
    map.setCenter(new OpenLayers.LonLat(90, -35), 7);
    
    // Add controls
    map.addControl(new OpenLayers.Control.MousePosition());
    map.addControl(new OpenLayers.Control.PanZoomBar());
    map.addControl(new OpenLayers.Control.LayerSwitcher({'ascending':true}));
    map.addControl(new OpenLayers.Control.ScaleLine());
    map.addControl(new OpenLayers.Control.Graticule());
  </script>
</body>
</html>
```

### Available Lunar Layers

<CardGroup cols={2}>
  <Card title="LOLA_color" icon="palette">
    Color-coded elevation visualization
  </Card>

  <Card title="LOLA_steel" icon="mountain">
    Grayscale elevation (steel colormap)
  </Card>

  <Card title="LOLA_bw" icon="image">
    Black and white shaded relief
  </Card>

  <Card title="LROC_WAC" icon="camera">
    Wide Angle Camera mosaic
  </Card>

  <Card title="UVVIS" icon="sun">
    Clementine UVVIS mosaic
  </Card>

  <Card title="KaguyaTC_Ortho" icon="satellite">
    JAXA Kaguya Terrain Camera
  </Card>

  <Card title="LO" icon="circle">
    Lunar Orbiter mosaic
  </Card>
</CardGroup>

## Leaflet Example

### Modern Lunar Web Map

Lightweight alternative using Leaflet:

```html theme={null}
<!DOCTYPE html>
<html>
<head>
  <title>WMS Example - Leaflet</title>
  <meta charset="utf-8" />
  <link rel="stylesheet" href="https://unpkg.com/leaflet@1.0.3/dist/leaflet.css" />
  <script src="https://unpkg.com/leaflet@1.0.3/dist/leaflet.js"></script>
  <style>
    #map { width: 600px; height: 400px; }
  </style>
</head>
<body>
  <div id='map'></div>
  <script type="text/javascript">
    // Define WMS layers
    var LROC_WAC = L.tileLayer.wms(
      'https://planetarymaps.usgs.gov/cgi-bin/mapserv?map=/maps/earth/moon_simp_cyl.map',
      { layers: 'LROC_WAC' }
    );
    
    var LOLA_color = L.tileLayer.wms(
      'https://planetarymaps.usgs.gov/cgi-bin/mapserv?map=/maps/earth/moon_simp_cyl.map',
      { layers: 'LOLA_color' }
    );

    // Initialize map
    var map = L.map('map', {
      crs: L.CRS.EPSG4326,
      center: [0, 0],
      zoom: 1,
      layers: [LROC_WAC, LOLA_color]
    });

    // Add layer control
    var baseMaps = {
      "LROC_WAC": LROC_WAC,
      "LOLA_color": LOLA_color
    };
    
    L.control.layers(baseMaps).addTo(map);
  </script>
</body>
</html>
```

### Adding GeoJSON Overlay

Include region of interest as GeoJSON:

```javascript theme={null}
// Define GeoJSON polygon
var pubextent = {
  "type": "FeatureCollection",
  "properties": {"title": "Example polygon"},
  "features": [{
    "type": "Feature",
    "properties": {},
    "geometry": {
      "type": "Polygon",
      "coordinates": [
        [[50, 22.5], [50, 27.5], [60, 27.5], [60, 22.5], [50, 22.5]]
      ]
    }
  }]
};

// Add to map
L.geoJson(pubextent).addTo(map);
```

### Custom Styling for GeoJSON

```javascript theme={null}
L.geoJson(pubextent, {
  style: {
    color: '#ff0000',
    weight: 2,
    opacity: 0.8,
    fillColor: '#ff0000',
    fillOpacity: 0.2
  },
  onEachFeature: function (feature, layer) {
    if (feature.properties.title) {
      layer.bindPopup(feature.properties.title);
    }
  }
}).addTo(map);
```

## Available WMS Endpoints

### USGS Astrogeology WMS Services

<Tabs>
  <Tab title="Moon">
    **Base URL:** `http://planetarymaps.usgs.gov/cgi-bin/mapserv?map=/maps/earth/moon_simp_cyl.map`

    **Available Layers:**

    * `LOLA_color` - LOLA elevation (color)
    * `LOLA_steel` - LOLA elevation (steel)
    * `LOLA_bw` - LOLA elevation (grayscale)
    * `LROC_WAC` - LROC Wide Angle Camera
    * `uv_v2` - Clementine UVVIS v2
    * `KaguyaTC_Ortho` - Kaguya Terrain Camera
    * `LO` - Lunar Orbiter

    **Elevation URL:** `http://wms.wr.usgs.gov/cgi-bin/mapserv?map=/maps/earth/moon_simp_cyl_elev.map`

    * `LOLA_elev` - LOLA elevation (Int16)
  </Tab>

  <Tab title="Mars">
    **Base URL:** `http://planetarymaps.usgs.gov/cgi-bin/mapserv?map=/maps/mars/mars_simp_cyl.map`

    **Available Layers:**

    * `MDIM21` - Mars Digital Image Mosaic 2.1
    * `THEMIS_IR_Day` - THEMIS Infrared Day
    * `THEMIS_IR_Night` - THEMIS Infrared Night
    * `Viking_MDIM21` - Viking MDIM 2.1

    **Elevation URL:** `http://wms.wr.usgs.gov/cgi-bin/mapserv?map=/maps/mars/mars_simp_cyl_elev.map`

    * `MOLA_elev` - MOLA elevation (Int16)
  </Tab>
</Tabs>

<Info>
  For a complete list of available layers, visit the [USGS Astro Web Map Atlas](http://astrowebmaps.wr.usgs.gov/webmapatlas/Layers/maps.html)
</Info>

## GetCapabilities Requests

### Query Available Layers

Get WMS capabilities to discover all available layers:

```bash theme={null}
curl "http://planetarymaps.usgs.gov/cgi-bin/mapserv?map=/maps/earth/moon_simp_cyl.map&SERVICE=WMS&REQUEST=GetCapabilities"
```

This returns an XML document listing:

* Available layers
* Supported formats
* Coordinate systems
* Bounding boxes
* Layer metadata

### Parse Capabilities with Python

```python theme={null}
from owslib.wms import WebMapService

wms = WebMapService('http://planetarymaps.usgs.gov/cgi-bin/mapserv?map=/maps/earth/moon_simp_cyl.map')

print(f"Title: {wms.identification.title}")
print(f"Layers: {list(wms.contents)}")

# Get layer details
for layer in wms.contents:
    print(f"\nLayer: {layer}")
    print(f"  Title: {wms[layer].title}")
    print(f"  BoundingBox: {wms[layer].boundingBox}")
```

## Advanced Techniques

### Transparent Overlays

Combine base imagery with transparent overlays:

```javascript theme={null}
// Leaflet example
var baseLayer = L.tileLayer.wms(wmsUrl, {
  layers: 'LROC_WAC',
  format: 'image/jpeg'
});

var overlayLayer = L.tileLayer.wms(wmsUrl, {
  layers: 'nomenclature',
  format: 'image/png',
  transparent: true
});

map.addLayer(baseLayer);
map.addLayer(overlayLayer);
```

### Time Series Animation

For temporal datasets with time parameter support:

```javascript theme={null}
var timeLayer = L.tileLayer.wms(wmsUrl, {
  layers: 'seasonal_data',
  time: '2023-01-01',
  format: 'image/png'
});

// Update time parameter
function updateTime(newTime) {
  timeLayer.setParams({ time: newTime });
}
```

### GetFeatureInfo Requests

Query pixel values from WMS layers:

```javascript theme={null}
map.on('click', function(e) {
  var url = LOLA_color.getFeatureInfoUrl(e.latlng, {
    query_layers: 'LOLA_elev',
    info_format: 'text/plain'
  });
  
  fetch(url)
    .then(response => response.text())
    .then(data => console.log('Elevation:', data));
});
```

## Performance Optimization

### Tile Caching

<Tip>
  For repeated access, consider setting up a local tile cache using MapProxy or TileCache to reduce server load and improve performance.
</Tip>

**MapProxy Configuration Example:**

```yaml theme={null}
sources:
  moon_wms:
    type: wms
    req:
      url: http://planetarymaps.usgs.gov/cgi-bin/mapserv?map=/maps/earth/moon_simp_cyl.map
      layers: LOLA_color

layers:
  - name: moon_cached
    title: Cached Moon Layer
    sources: [moon_wms]

caches:
  moon_cache:
    grids: [EPSG4326]
    sources: [moon_wms]
```

### Request Optimization

```javascript theme={null}
// Use appropriate tile size
var layer = L.tileLayer.wms(url, {
  layers: 'LOLA_color',
  tileSize: 512,  // Reduce number of requests
  maxZoom: 10      // Prevent excessive detail requests
});
```

## Troubleshooting

### Common Issues

**Issue:** "Service not found" error\
**Solution:** Verify the map file path in ServerUrl is correct

**Issue:** Blank tiles or no data\
**Solution:** Check DataWindow coordinates are within valid range (Lon: -180 to 360, Lat: -90 to 90)

**Issue:** Slow performance\
**Solution:** Reduce SizeX/SizeY values, use appropriate image format (JPEG for imagery, TIFF for elevation)

**Issue:** Coordinate system mismatch\
**Solution:** Ensure EPSG:4326 is specified in both Service/SRS and Projection elements

## Source Files Reference

* `gdal_MDIM21.xml` - Mars MDIM 2.1 configuration
* `gdal_mars_MOLA_elev.xml` - Mars MOLA elevation configuration
* `gdal_moon_LOLA_elev.xml` - Moon LOLA elevation configuration
* `OpenLayers_MyMoon.html` - OpenLayers implementation example
* `leaflet_moonWMS2_wGeoJSON_Box.html` - Leaflet implementation example

## Additional Resources

<CardGroup cols={2}>
  <Card title="USGS Astro Web Maps" icon="globe" href="http://astrowebmaps.wr.usgs.gov/webmapatlas/Layers/maps.html">
    Complete layer catalog and documentation
  </Card>

  <Card title="GDAL WMS Driver" icon="file-code" href="https://gdal.org/drivers/raster/wms.html">
    GDAL WMS driver documentation
  </Card>

  <Card title="OpenLayers API" icon="map" href="https://openlayers.org/">
    OpenLayers documentation and examples
  </Card>

  <Card title="Leaflet Documentation" icon="leaf" href="https://leafletjs.com/">
    Leaflet API reference and tutorials
  </Card>
</CardGroup>

## See Also

* [OGC WMS Specification](https://www.ogc.org/standards/wms)
* [GDAL Virtual File Systems](https://gdal.org/user/virtual_file_systems.html)
* [IAU Planetary Projections](/planetary/iau-projections)