Geospatial Concepts, Technologies, and Applications

Comprehensive practice flashcards covering GIS fundamentals, coordinate reference systems, geocoding, vector and raster data models, attribute levels of measurement, cartographic map design, remote sensing technologies, GeoBIM integration, and the GeoData life cycle with real-world case studies.

What is geocoding?

Geocoding is the process of finding geographic coordinates (such as latitude/$y$ and longitude/$x$ in decimal format) for a physical address to identify a location on the Earth's surface.

What reference coordinate system do returned geocoding coordinates typically use?

They use $\text{WGS 84}$, which is sometimes designated as $\text{EPSG:4326}$.

What is reversed geocoding?

Reversed geocoding is the process of converting geographic coordinates back into a human-readable address or place name.

How do lines of latitude and longitude differ in their orientation across the globe?

Lines of latitude run in an east-west direction across the Earth, whereas lines of longitude run in a north-south direction.

What are the three geometry types used in the vector data model, and what dimensionality does each represent?

1. Point: $XY$ coordinate pairs that are zero-dimensional (e.g., trees, bus stops, lampposts).\n2. Line: A series of connected points that are one-dimensional (e.g., rivers, roads, canals).\n3. Polygon: A set of connected vertices in a particular order forming a closed enclosure that is two-dimensional (e.g., buildings, boundaries, lakes).

What is a raster data model, and what types of values can its cells contain?

A raster data model represents the world through a matrix of cells or pixels organized into rows and columns (a grid). The value of each cell can be continuous (such as elevation) or discrete/categorical (such as land use).

What are the two major spatial properties characterizing raster datasets?

1. Extent: The spatial boundary defined by coordinates ($X_{\min}$, $Y_{\max}$, $X_{\max}$, $Y_{\max}$, $X_{\min}$, $Y_{\min}$, $X_{\max}$, $Y_{\min}$).\n2. Resolution: The physical size represented by each cell or pixel (e.g., $8\,\text{m}$, $4\,\text{m}$, $2\,\text{m}$, or $1\,\text{m}$).

What is the Modifiable Areal Unit Problem (MAUP)?

MAUP is a statistical bias in GIS that occurs when point data is aggregated into geographic units, causing spatial analysis results to vary depending on the arbitrary delineation and choice of spatial boundaries.

What are the two distinct effects that produce bias in the Modifiable Areal Unit Problem (MAUP)?

1. Scale effect: Occurs when analytical results change based on the level or size of aggregation (e.g., moving from smaller to larger boundary units).\n2. Zonal effect: Occurs when aggregating data into different artificial boundary configurations at the same scale (e.g., grouping points by county versus by state).

What are the four common data types used for vector attributes in GIS?

1. Integers: Whole numbers (e.g., $1$, $8717$, $-50$).\n2. Float or Real: Decimal numbers (e.g., $1.545$, $21{,}576.1$, $-248.751$).\n3. Text or String: Character sequences (e.g., 'A', 'Geospatial', 'Blk 233 Yishun St.').\n4. Date: Temporal values in formats such as $\text{dd/mm/yy}$ or $\text{yyyy/mm/dd}$.

What are the four levels of attribute measurement from qualitative to quantitative?

1. Nominal Data: Categories without natural ordering or direction (qualitative).\n2. Ordinal Data: Ordered categories representing rankings, scaling, or order (qualitative).\n3. Interval Data: Differences between measurements exist, but there is no true zero (quantitative).\n4. Ratio Data: Differences between measurements exist, and a true zero point exists (quantitative).

What are the nine primary cartographic elements required in effective map design?

1. Title\n2. Subtitle\n3. Legend\n4. Maps\n5. North arrow\n6. Date\n7. Authorship\n8. Scale bars\n9. Page border

What is remote sensing?

Remote sensing is the science of obtaining the physical properties of an area without being physically present, allowing users to capture, visualize, analyze, and classify objects and surface features into land cover and other categories.

How do active and passive remote sensing sensors differ?

Active sensors provide their own source of illumination by sending out an energy pulse toward the target and measuring the reflected backscatter (e.g., Radarsat-2 using SAR). Passive sensors measure naturally reflected electromagnetic energy emitted from the sun (e.g., Landsat and Sentinel).

What are the definitions of spatial, spectral, and temporal resolution in remote sensing?

1. Spatial Resolution: The level of detail per pixel; high spatial resolution indicates smaller pixel sizes and finer detail.\n2. Spectral Resolution: The amount of spectral detail per band; high spectral resolution features narrow wavelength bands.\n3. Temporal Resolution: The revisit time required for a satellite to complete an orbit and revisit the same area.

What are the three main types of satellite orbits by movement characteristics?

1. Geostationary orbits: Match the Earth's rotational speed, appearing fixed over one location.\n2. Sun-synchronous orbits: Maintain a consistent sunlight illumination angle on the Earth's surface.\n3. Polar orbits: Pass above or nearly above both geographic poles.

Which orbit altitude tier hosts Global Positioning System (GPS) satellites, and why?

GPS satellites are located in Medium Earth Orbit ($\text{MEO}$). Their continuous orbital path produces consistent revisit times, allowing a GPS receiver to lock onto $\ge 3$ satellites for high positioning accuracy.

What is the primary difference in application environment between LiDAR and Sonar?

While both technologies measure distances to generate digital elevation models ($\text{DEMs}$), LiDAR (Light Detection and Ranging) is best suited for terrestrial ground surfaces, whereas Sonar (Sound Navigation Ranging) operates underwater.

What is a Geographic Information System (GIS)?

GIS is a multi-component environment designed to create, manage, visualize, and analyze data along with its spatial counterpart.

What is a datum in geodesy and GIS?

A datum is a mathematical model of the Earth that specifies:\n1. Angular units (e.g., degrees)\n2. A starting origin reference point ($0,0$)\n3. The position and orientation of an ellipsoid/spheroid relative to the Earth's center of mass.

Which horizontal and vertical datums are used in Singapore?

For horizontal datums, $\text{WGS 84}$ is used for global mapping and $\text{SVY21}$ is used for local mapping. For vertical datums, the Singapore Height Datum ($\text{SHD}$) is used.

What are the three developable surface families used to classify Projected Coordinate Systems (PCS)?

1. Planar (Azimuthal) projections: Project onto a flat plane touching at a point or circle.\n2. Conical projections: Project onto a cone touching along lines of tangency/secancy.\n3. Cylindrical projections: Project onto a cylinder wrapped around the globe.

Which four spatial properties can a map projection distort or preserve, none of which can all be preserved simultaneously?

1. True Area\n2. True Direction\n3. True Distance\n4. True Shape

What is Building Information Modeling (BIM)?

BIM is a process involving the generation and management of digital representations of physical and functional characteristics of places, creating virtual models embedded with geometric and non-geometric property data.

What do the components 'B', 'I', and 'M' stand for in BIM?

1. 'B' (Building): The process of collaborative construction across architecture, engineering, and infrastructure.\n2. 'I' (Information): Embedded geometric data (e.g., $400 \times 800 \times 6700\,\text{mm}$, volume $2.152\,\text{m}^3$) and non-geometric data (e.g., Concrete Grade $40$, fire rating, warranties, pricing).\n3. 'M' (Modelling): Digital virtual representation used to visualize design, manage construction, and operate/maintain buildings.

What are the primary differences between GIS and BIM in GeoBIM integration?

BIM deals with the specific and micro-scale (detailed structural elements, individual materials, focused on Design and Build phases). GIS deals with the broad and macro-scale (regional spatial phenomena, geographic features, focused on Plan and Operate phases).

What are the four sequential stages of the GeoData Life Cycle?

1. Collect: Acquiring primary/secondary, qualitative/quantitative data via sensors, surveys, or crowdsourcing.\n2. Combine: Fusing, aggregating, and reclassifying disparate layers using common identifiers or spatial reference.\n3. Collaborate: Storing and sharing data on platforms (e.g., GeoPortals, GeoSpace) with standardized formats and security.\n4. Consume: Unlocking value via spatial modeling, predictions, cluster analysis, and cartographic visualizations.

In the Northern Singapore elderly and crime case study, what was the correlation between crime numbers and distance to the nearest Neighbourhood Police Centre (NPC)?

Pearson's correlation coefficient was $r = -0.4204$, indicating an inverse relationship and showing that simply adding more NPCs does not decrease crime counts.

According to the SLA sports accessibility study, what proportion of residents lived within a 10-minute walk of a sports facility as of 2017, and which two planning areas were identified as lacking facilities?

As of $2017$, $78\%$ of residents were within a $10$-minute walk. Marine Parade and Bukit Timah were identified as lacking facilities, leading to recommendations for elder-friendly sports sites (locations A through F).

In Singapore's 2019 park accessibility analysis, what percentage of residential buildings were within a 10-minute walk from a park, and what property type represented the largest share outside this zone?

$90.9\%$ ($105{,}602$ buildings) were within a $10$-minute walk ($60.7\%$ within $5\,\text{mins}$, $97.9\%$ within $15\,\text{mins}$). Landed properties accounted for the highest proportion of buildings ($79.4\%$) located beyond a $10$-minute walk.

How did student travel distances compare between Government and Government-aided schools in the Singapore primary school bus travel study?

Government-aided schools had a longer average travel distance than Government schools, likely due to larger alumni networks and affiliations associated with Government-aided institutions.

How do commercial platforms Grab and RedMart utilize geospatial technology to optimize operations?

Grab uses location data to determine the most optimum routes and passenger pick-up points. RedMart groups customer orders based on geographic location to lower logistics and delivery costs.