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Hong Kong 1980 Grid (Hong Kong 1980 Coordinate System | EPSG:2326) is a regional projected coordinate system specially designed for Hong Kong's urban surveying and mapping needs during the late 20th century. Developed as part of Hong Kong's territorial surveying framework, this system employs a transverse Mercator projection centered on the region's specific geographical characteristics. Although now supplemented and partially superseded by modern geocentric systems, it remains crucial for processing legacy engineering plans, cadastral records, and historical urban data from Hong Kong's development boom period.

Xian 1980 (Xi'an 1980 Coordinate System | EPSG:4610) is a Chinese national geodetic datum established in the 1980s as an improved successor to the Beijing 1954 system. It was developed to address the limitations of the earlier non-geocentric datum and to better support China's growing surveying, mapping, and infrastructure needs. Based on the IAG 1975 ellipsoid with a geocentric origin, Xian 1980 represented a significant step toward modern geodetic standards in China. Although now superseded by the fully geocentric CGCS2000, it remains important for processing data from the late 20th century and serves as a transitional benchmark in China's geodetic evolution.

Beijing 1954 (Beijing 1954 Coordinate System, EPSG:4214) is a national geodetic datum established in China during the 1950s. As the first nationwide unified coordinate system introduced after the founding of the People’s Republic of China, it is a non-geocentric (local) datum designed for nationwide surveying and mapping. It was developed with reference to the Soviet geodetic framework and is based on the Krasovsky 1940 ellipsoid. This coordinate system was used extensively across China for foundational surveying, topographic mapping, infrastructure construction, and land administration over a long period, forming the basis of China's surveying and mapping system in the latter half of the 20th century. Although it has now been officially replaced by the more precise and geocentric CGCS2000, it still plays a significant role in processing historical and legacy data.

Batavia (Batavia Datum | EPSG:4211) is a region-specific, non-geocentric datum used primarily in the former Dutch East Indies (present-day Indonesia) during the early 20th century. Established to support colonial administration, topographic surveying, cadastral mapping, and infrastructure development, it served as a unified reference for surveying and mapping centered around Java. Today, it has been entirely replaced by modern geocentric coordinate systems such as ITRF and WGS84. Its practical relevance is now largely confined to the conversion and analysis of historical maps and legacy survey data.

The OpenAerialMap API is a public API service for sharing and accessing aerial and drone imagery (aerial photographs and orthoimagery) operated under the principles of open source. It is primarily led by communities such as the Humanitarian OpenStreetMap Team (HOT) and provides access to metadata and actual imagery data worldwide for purposes including disaster response, humanitarian aid, research, and public use. Through the API, users can search and retrieve aerial imagery based on criteria such as geographic area, acquisition date, resolution, and license terms, promoting the reuse and transparency of geospatial data.

USGS EarthExplorer is an official geospatial data search and distribution platform provided by the United States Geological Survey (USGS). It primarily offers a diverse range of remote sensing and terrain data—including satellite imagery, aerial photographs, digital elevation models (DEM), and land cover data—free of charge. EarthExplorer features a web‑based interface and also supports automated access via an Application Programming Interface (API), providing researchers and engineers with an efficient environment for acquiring and processing large‑scale data.

The Planet Labs API is an API provided by the US-based company Planet Labs for delivering Earth observation satellite data. It is characterized by its ability to programmatically search, retrieve, and analyze satellite imagery captured by a large number of small Earth observation satellites (known as the "Dove" constellation), offering high-frequency and high-temporal-resolution data. A key strength lies in its "daily revisit" capability, enabling near-real-time monitoring of surface changes—a significant departure from traditional satellite data services.

DigitalGlobe / Maxar Imagery API is a commercial satellite imagery delivery service and set of APIs provided by Maxar Technologies (formerly DigitalGlobe) in the United States. It is characterized by its ability to deliver sub-meter resolution optical satellite imagery, captured by high-performance Earth observation satellites such as WorldView and GeoEye, through an online API. Users can flexibly search, visualize, and download both the latest and archived imagery, making it a key foundational service for geospatial analysis, decision support, and both commercial and public applications.

The Mapillary Map Traces / GPX service is an interface for providing trajectory data accompanying street-level imagery collection, offered by Mapillary. It enables the publication and retrieval of movement paths (traces) corresponding to street-level images captured and uploaded by users as geospatial data. Primarily delivered in standard formats such as GPX, it provides user movement trajectories—from walking, cycling, or driving—as time‑series coordinate data, allowing spatially‑linked analysis and visualization alongside street‑level imagery. These trace data are highly compatible with open‑map ecosystems like OpenStreetMap (OSM) and serve as an important supplementary data source for real‑world road and route information.

LY (Polygon File Format / Stanford Triangle Format) is a file format for three-dimensional data primarily used in 3D scanning and computer graphics. Originally developed at Stanford University, it is characterized by its ability to flexibly describe not only shape information such as point clouds and polygon meshes but also attributes like color, normal vectors, and transparency. With a simple yet highly extensible structure, PLY is widely utilized across research and industrial applications, playing a key role in areas such as 3D modeling, visualization, reverse engineering, and digital preservation of cultural heritage.