Introduction

Satellite imagery, aerial photos, digital elevation models (DEMs), and other raster datasets are fundamental to geospatial analysis. Historically, viewing these files required desktop GIS software like QGIS or ArcGIS, or uploading them to a remote service — neither of which is ideal for quick inspection.

GeoDataViewer now supports GeoTIFF and Cloud Optimized GeoTIFF (COG) files directly in your browser, with zero uploads and instant visual feedback.

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1. What is a GeoTIFF / COG?

GeoTIFF

A GeoTIFF is a standard TIFF image file that embeds georeferencing metadata — projection, coordinate system, pixel scale, and geographic extent — directly into the file. It is the most widely used raster format in GIS, compatible with virtually every geospatial tool.

Cloud Optimized GeoTIFF (COG)

A COG is a GeoTIFF structured for efficient HTTP range-request access. Instead of downloading the entire file, a COG client can request only the tiles and resolution levels it needs. This makes COG ideal for cloud-hosted and web-based GIS workflows, enabling fast pan and zoom even for very large raster datasets.

GeoDataViewer supports both standard GeoTIFF files (local drag-and-drop) and remote COG URLs (via HTTP).

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2. How to Load a COG / GeoTIFF in GeoDataViewer

Drag and Drop

Simply drag a .tif or .tiff file from your file system onto the GeoDataViewer map. The file is processed entirely in your browser — no upload, no server round-trip.

Remote URL (COG)

You can also load a remote COG by pasting its URL. The app streams only the tiles needed for the current viewport, thanks to the COG’s internal tile structure.

Once loaded, the raster appears in the Workspace panel under the Layers tab, alongside any vector datasets you have open.

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3. Raster Visualization Controls

GeoDataViewer provides a full set of raster rendering controls, styled consistently with the vector layer panel.

Band Mode

For multi-band imagery (e.g., 3-band RGB satellite data), you can switch between:

• RGB mode — standard true-color or false-color composite. Select which band maps to the R, G, and B channels.
• Single Band mode — display a single band with a color ramp, ideal for NDVI, elevation, or thermal data.

Color Ramps (Single Band)

When rendering a single band, choose from a variety of color ramps:

viridis · plasma · inferno · magma · gray · turbo · rainbow · cividis · coolwarm · rdylbu · greens

Opacity

Control layer transparency independently, useful when overlaying raster data on top of vector features or basemaps.

Gamma Correction

Adjust the gamma curve to brighten or darken midtones without clipping highlights or shadows — useful for correcting overly dark or washed-out imagery.

Stretch

• Linear — default contrast stretch
• Equalize — histogram equalization for enhanced contrast

No-Data Value

Specify a pixel value to treat as transparent (e.g., 0 or -9999), commonly used in satellite imagery to mask out invalid pixels.

Rescale

Set custom min/max values per band for contrast scaling, giving you fine-grained control over how pixel values map to display colors.

CRS Information

The native CRS of the raster is displayed as a badge, so you always know which projection the source data uses.

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4. DEM (Digital Elevation Model) Support

When a GeoTIFF is detected as a DEM (based on band characteristics), GeoDataViewer renders it as 3D terrain using MapLibre’s native raster-dem and hillshade layers. The elevation data interacts with the globe projection for a true 3D experience.

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5. Technical Implementation

GeoDataViewer renders COG and GeoTIFF files using:

• geotiff.js — client-side GeoTIFF parsing and band metadata extraction
• maplibre-gl-raster — WebGL-powered raster tile rendering on the map
• URL.createObjectURL — local files are accessed via blob URLs, never uploaded

All processing happens in the browser using WebAssembly and JavaScript — your data stays on your machine.

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6. Use Cases

Scenario	How GeoDataViewer Helps
Quick satellite image check	Drag a GeoTIFF onto the map — immediate visualization
DEM elevation inspection	Drop a DEM file, see 3D terrain with hillshading
Multi-band compositing	Switch between RGB bands to create false-color composites
Remote COG exploration	Paste a COG URL, stream tiles on demand
Raster + vector overlay	Load both raster imagery and vector data in the same workspace

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Getting Started

1. Open GeoDataViewer
2. Drag a .tif / .tiff file onto the map, or paste a COG URL
3. Use the Workspace panel to adjust rendering
4. No sign-up, no upload — your data never leaves your browser

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GeoDataViewer is a free, local-first GIS data viewer and converter supporting 20+ geospatial formats.