GELE Photogrammetry & Cartography Reviewer 2026

Answer: A. To represent the curved surface of the Earth on a flat plane

Step 1: Recall the core problem in cartography — the Earth is an oblate spheroid (3D), but maps are flat (2D). Step 2: A map projection is a systematic mathematical transformation that 'flattens' the curved surface onto a developable plane. Step 3: Option A is correct — this is the defining purpose of any projection. Step 4: Option B is wrong because distortion is unavoidable; every flat map distorts something (area, shape, distance, or direction). Step 5: Options C and D describe other geodetic operations, not the definition of a map projection.

Answer: B. Conformal (orthomorphic) projection

Step 1: The key term is 'preserves angles and local shape.' Step 2: Conformal (also called orthomorphic) projections maintain angular relationships at every point, meaning a small circle on the ellipsoid plots as a small circle on the map. Step 3: Equal-area projections preserve area, not angles — they are the opposite property. Step 4: Equidistant projections preserve distance only along certain lines, not angles. Step 5: Azimuthal refers to a type of developable surface (planar), not a preserved property — an azimuthal projection can be conformal, equal-area, or equidistant.

Answer: B. 9 996.00 m

Step 1: Recall the formula: grid distance = k × ellipsoidal distance. Step 2: Substitute values: grid distance = 0.99960 × 10 000.00 m. Step 3: Compute: 0.99960 × 10 000.00 = 9 996.00 m. Step 4: Since k < 1, the grid distance is shorter than the ellipsoidal distance — this is expected near the central meridian of a Transverse Mercator projection. Step 5: Option A (10 004.00 m) would result from k > 1 (zone edge), Option C assumes no correction (k = 1), and Option D uses an incorrect k.

Answer: D. 0.99960 (k₀ = 0.9996)

Step 1: UTM is a Transverse Mercator projection applied globally in 6° zones. Step 2: To control overall distortion within each zone, UTM deliberately sets the scale factor at the central meridian to k₀ = 0.9996 (slightly less than 1). Step 3: This means the two standard lines (where k = 1 exactly) fall about 180 km on each side of the central meridian. Step 4: k < 1 at the central meridian means grid distances are slightly shorter than ellipsoidal distances there; k > 1 near the zone edges. Step 5: k₀ = 1.0000 would describe a standard (non-reduced) Transverse Mercator, not UTM.

Answer: C. Transverse Mercator projection

Step 1: The PPCS (Philippine Plane Coordinate System), defined under NAMRIA and referenced to PRS92, uses the Transverse Mercator (TM) projection — the same mathematical basis as UTM. Step 2: TM is conformal, preserving angles locally, which makes it ideal for surveying and engineering computations in the Philippines. Step 3: The Mercator projection (Option A) is the standard (equatorial) cylinder version, unsuitable for a country spanning longitudes 116°–127°E. Step 4: Albers (Option B) is an equal-area conic — useful for area maps but not for surveying grids. Step 5: Lambert Conformal Conic (Option D) is used in some countries' survey grids but not in the Philippine PPCS/UTM.

Answer: C. Cylinder

Step 1: Projections are classified by the geometric surface onto which the Earth is 'projected' before unrolling. Step 2: The three developable surfaces are: cylinder (cylindrical), cone (conic), and plane (azimuthal/planar). Step 3: The Mercator projection — in both its normal (equatorial) and transverse forms — wraps a cylinder around the Earth. Step 4: Conic projections (e.g., Albers, Lambert CC) use a cone; azimuthal projections (e.g., Stereographic) use a flat plane. Step 5: An ellipsoid is the reference surface for the Earth itself, not a developable projection surface.

Answer: C. Equal-area — to preserve area

Step 1: The purpose is area comparison among provinces, so the map must represent area faithfully. Step 2: An equal-area (equivalent) projection ensures that any region on the map has the same area proportion as on the ellipsoid — provinces can be directly compared by their map sizes. Step 3: Conformal projections sacrifice area to preserve angles — Mercator, for example, greatly exaggerates area at high latitudes. Step 4: Equidistant preserves distance only along specific lines, not area. Step 5: Azimuthal describes a surface type, not a preserved property; it can be combined with different properties but is not the defining answer here.

Answer: B. Along the two standard lines, located ~180 km from the central meridian

Step 1: On a TM projection with k₀ < 1, the scale factor varies across the zone. Step 2: At the central meridian, k = k₀ = 0.9996 (less than 1, meaning slight compression). Step 3: Moving away from the central meridian, k increases. At two symmetric lines (~180 km each side for UTM), k rises back to exactly 1.0000 — these are the standard lines (also called lines of zero distortion). Step 4: Beyond the standard lines toward the zone edges, k exceeds 1.0000 (slight expansion). Step 5: Zone boundaries have k > 1; the equator is a geographic line unrelated to scale factor variation in TM.

Answer: B. It preserves angles locally, so measured bearings transfer to the grid with minimal distortion

Step 1: Cadastral surveys and traverse computations rely heavily on measured angles and bearings. Step 2: A conformal projection preserves angles at every point — horizontal angles measured in the field match angles on the projection grid. Step 3: This means surveyors can compute traverses directly on the grid without applying angular corrections for projection distortion. Step 4: Option A is wrong — conformal projections distort area (e.g., Mercator exaggerates Greenland). Step 5: Option C is wrong — scale factor corrections (k) are still applied for distances. Option D is a distractor; PD 1529 (Property Registration Decree) governs land registration but does not specifically mandate a projection type.

Answer: B. Every flat map projection introduces some form of distortion

Step 1: This is a fundamental theorem of map projection — it is mathematically impossible to flatten a sphere or ellipsoid onto a plane without distorting at least one of: area, shape, distance, or direction. Step 2: Option A contradicts this theorem; no such perfect projection exists. Step 3: Option C is false — Mercator is ideal for navigation (conformal, rhumb lines are straight) but badly distorts area at high latitudes. Step 4: Option D is subtly wrong — a conformal projection preserves angles (local shape) but still distorts area and distances; it does not have zero distortion everywhere. Step 5: Distortion on a conformal map is only zero at the standard line(s); k varies everywhere else.

Answer: B. 60 zones

Step 1: Recall the UTM design — the Earth's 360° of longitude is divided into equal-width columns called zones. Step 2: Each zone spans 6° of longitude (360° ÷ 6° = 60 zones). Step 3: Zones are numbered 1 to 60 eastward, starting from the 180° meridian. Step 4: Option A (30 zones) would imply 12°-wide zones — incorrect. Option C (90) implies 4°-wide zones — incorrect. Option D (120) implies 3°-wide zones — incorrect. The correct answer is 60 zones, each 6° wide.

Answer: C. 0.9996

Step 1: In Transverse Mercator projections, the central meridian scale factor k₀ is deliberately set below 1.0 to reduce overall distortion across the zone. Step 2: For UTM, k₀ = 0.9996 — meaning the central meridian is slightly contracted (scale < 1), so two secant lines within the zone have true scale (k = 1), balancing distortion. Step 3: The value 0.99995 belongs to the Philippine Plane Coordinate System (PPCS), not UTM — a common board-exam trap. Step 4: k₀ = 1.0000 would describe an ordinary Transverse Mercator with no scale reduction at the CM. Step 5: Therefore, k₀ = 0.9996 is the correct UTM value.