Exame GIS

A map projection where the projection paper cuts through the Earth's surface, minimizing average scale error.

A map projection where the projection paper touches the Earth's surface along a meridian.

The line of longitude used as the reference point in a map projection.

A common scale for detailed reference maps, showing a large amount of detail.

Key features on a map used for orientation and reference (e.g., water bodies, roads).

A terrain map shows land cover, topography, infrastructure, urban areas, and hydrology.

Cylindrical projection where the projection cylinder cuts through the Earth at two points.

Cylindrical projection rotated to follow the central meridian of a particular region.

A differential GPS method that uses multiple reference stations to compensate for atmospheric errors, like ions and electrical conductivity, to improve positioning accuracy.

A differential GPS method using one reference station for positioning, often less accurate than network RTK due to reliance on a single reference point.

The national Swedish network of positional reference stations used in various differential GPS methods.

A map where polygons (like counties/regions) represent a single constant attribute value like population density or another attribute.

A map where symbols carry different attribute values, rather than representing just one. For example, the speed and direction of a current.

Maps that distort area or distance to emphasize an attribute (rather than showing actual geographic areas accurately).

A sensor that relies on external light sources, like the sun, to gather information.

A sensor that emits its own signals (like radar or sonar) to bounce back for data collection.

Raster data is simple to structure, can store continuous surfaces like temperature, and represents fuzzy objects like wetlands. It's good for visualizing continuous phenomena like elevation.

Raster data lacks topology (spatial relationships between features), requiring large storage space, and can lead to inaccuracies when representing precise shapes.

Vector data has exact geometry, accurately represents shapes, can store multiple attributes for each object, and defines spatial relationships with topology, thus representing connectivity and adjacency.

Vector data can be computationally complex for analysis, lacks representation of continuous phenomena, and may be overly precise in some contexts, lacking data for regions.

Spatiotemporal data reflects how geographic features change over time. Use raster data to gather temporal snapshots during change periods (monthly, yearly, or seasonal) to visualize change.

The geoid is a gravity-based surface approximating Earth's shape. To capture local gravity, a local ellipsoid is used to approximate local curvature of the geoid, maintaining the connection to the global ellipsoid while providing a mathematically defined surface.

Secant projections minimize average scale error compared to tangential projections, as the projection cylinder cuts through the Earth at two points.

Secant projections provide a balance of accuracy across a larger area by minimizing average scale error, while tangential projections are more accurate at the point of tangency but have higher distortion elsewhere.