Memory AnchorsGELE · Photogrammetry & CartographyReal content

GELE Photogrammetry & Cartography — Map ProjectionsMemory Anchors

Summary Concepts Notes Revision Deep Dive Slides Flashcards Mistakes Cheat Mnemonics Templates

Under the clock, Map Projections facts fade unless they have a hook. Mnemonics are the hook. This page collects the memory anchors that reliably work for Filipino GELE candidates on Professional Regulation Commission (PRC) — Board of Geodetic Engineering's Photogrammetry & Cartography items — acronyms, visual pairings, and short rhymes you can rehearse on your commute.

Exam context

Professional Regulation Commission (PRC) — Board of Geodetic Engineering runs the Geodetic Engineer Licensure Examination on September 2026. Its Photogrammetry & Cartography section sits under a "Core" weighting, and Map Projections is the 4th chapter in the 6-chapter GELE Photogrammetry & Cartography rotation. The GELE passing mark is 70% weighted average, no sub-test below 50%, and the most recent 2026 paper drew about a meaningful share of questions from Photogrammetry & Cartography.

Map Projections - Memory Anchors

Memory anchors are cognitive shortcuts that link unfamiliar technical concepts to vivid, emotionally engaging images, stories, or sounds already stored in long-term memory. Research shows that encoding information through multiple pathways — verbal, visual, emotional, and kinesthetic — can improve recall by up to 400% compared to passive re-reading. For the PRC board exam, where you must recall dozens of definitions, formulas, and classifications under pressure, having a ready-made mental 'hook' for each concept is a decisive advantage. The anchors in this chapter use mnemonics, analogies drawn from Filipino everyday life, micro-stories set in familiar Philippine contexts, and Mermaid visual maps to make every key concept in Map Projections unforgettable. Work through each anchor once, visualize it clearly, then test yourself with the recall trigger. Return to the revision game weekly to keep the memories fresh.

Anchors

Topic

Nature of Map Projections

Concept

No projection preserves area, shape, distance, AND direction simultaneously

Anchor Id

Difficulty

easy

Memory Aid

Imagine trying to flatten a whole lansones fruit skin onto a table without tearing it. No matter how carefully you press it, some part will stretch, tear, or compress. The Earth's curved surface is the lansones peel — every time you try to lay it flat, something is sacrificed. You can choose WHICH part gets distorted, but you cannot avoid distortion entirely.

Anchor Type

analogy

Why It Works

The tactile, everyday image of peeling fruit is universally relatable to Filipino students and creates a strong sensory memory. The frustration of a tearing peel maps directly onto the mathematical impossibility of a perfect projection.

Example Usage

Exam question: 'Can a single map projection preserve area, shape, distance, and direction?' Answer: No — recall the lansones peel. Something always tears. State: 'No projection preserves all four properties simultaneously because projecting a curved surface onto a plane necessarily introduces distortion in at least one property.'

Recall Trigger

Lansones peel on a flat table

Topic

Projection Properties

Concept

Three projection properties: Conformal (angles/shape), Equal-area (area), Equidistant (distance)

Anchor Id

Difficulty

easy

Memory Aid

Remember the acronym **CEE** — like the Filipino exclamation 'Ce!' (a surprised gasp when something is impressive): C = Conformal (preserves angles/shape), E = Equal-area (preserves area), E = Equidistant (preserves distance). When you see a projection question, gasp 'CEE!' and list the three properties.

Anchor Type

acronym

Why It Works

Acronyms reduce cognitive load by collapsing a list into a single retrievable cue. The Filipino exclamation adds emotional tagging, making the memory more vivid and personally meaningful.

Example Usage

Exam question: 'Enumerate the three main properties a map projection can preserve.' Think 'CEE!' → Conformal, Equal-area, Equidistant. Write all three with brief definitions.

Recall Trigger

'CEE!' — the Filipino gasp of surprise

Topic

Conformal Projections

Concept

Conformal projection preserves angles/shape locally (e.g., Mercator, Transverse Mercator)

Anchor Id

Difficulty

medium

Memory Aid

Think of a conformal projection as a strict mathematics teacher — she always preserves the ANGLE at which two lines meet, no matter how she stretches the paper. 'Con-form' literally means 'same shape.' The teacher's protractor reading is always correct at every intersection point on her map. Mercator and Transverse Mercator are the 'strict math teachers' of projections.

Anchor Type

analogy

Why It Works

Personifying the projection as a familiar authority figure (a strict teacher) creates an emotional and narrative hook. The word breakdown (con = same, form = shape) reinforces etymology-based recall.

Example Usage

Question: 'Why are survey grids (UTM/PPCS) based on a conformal projection?' Recall the strict math teacher — she preserves angles. Surveying needs correct angles (bearings, traverse angles) → conformal projection is required.

Recall Trigger

Strict math teacher with a protractor

Topic

Equal-Area Projections

Concept

Equal-area projection preserves area (e.g., Albers) — used for thematic/statistical maps

Anchor Id

Difficulty

easy

Memory Aid

Engineer Josie is preparing a national land-use thematic map for the DENR. Her boss insists: 'Every province must look exactly as big as it really is — we're comparing agricultural areas!' Josie chooses the Albers Equal-Area projection. When her boss checks Mindanao versus Luzon on the map, the area ratios match reality perfectly — but the shapes of the provinces look a bit squished at the edges. Josie explains: 'Sir, we saved the area; shape was sacrificed. That's the deal with equal-area projections.'

Anchor Type

micro_story

Why It Works

A concrete professional scenario in a Philippine agency context (DENR) makes the concept immediately relevant and memorable. The trade-off (area preserved, shape sacrificed) is dramatized through dialogue.

Example Usage

Question: 'A national statistics map must compare province areas fairly. What projection property is needed?' Recall Josie → Equal-area (equivalent) projection, e.g., Albers. Area is preserved; shape may be distorted.

Recall Trigger

Josie at the DENR comparing province sizes

Topic

Projection Classification by Developable Surface

Concept

Three developable surfaces: Cylindrical, Conic, Azimuthal (Planar)

Anchor Id

Difficulty

easy

Memory Aid

Use the mnemonic **'CCA'** — 'CCA' like 'Siya!' (Filipino for 'That's it!'): C = Cylindrical (wrap a cylinder around the globe), C = Conic (wrap a cone), A = Azimuthal/Planar (place a flat plane tangent to the globe). Alternatively, remember the sentence: **'Can Cows Actually fly?'** — Can = Cylindrical, Cows = Conic, Actually = Azimuthal.

Anchor Type

mnemonic

Why It Works

Both options (acronym and sentence mnemonic) give redundant retrieval paths. The absurd image of flying cows is inherently memorable due to its bizarreness, which activates the brain's novelty response.

Example Usage

Question: 'Classify the Mercator projection by developable surface.' Recall 'Can Cows Actually fly' → Mercator wraps a Cylinder → Cylindrical projection.

Recall Trigger

Flying cows / 'Siya!' — CCA

Topic

Transverse Mercator Projection

Concept

Transverse Mercator (TM) — cylinder axis is perpendicular to the polar axis (tangent to a meridian)

Anchor Id

Difficulty

medium

Memory Aid

Picture a giant can of San Miguel Beer lying on its SIDE (horizontal), pressed against the surface of the globe along a meridian (north-south line). The regular Mercator can stands UPRIGHT touching the equator; the Transverse Mercator can is TIPPED 90° on its side touching a meridian. 'Transverse' = tipped sideways. This is how TM grids like UTM and PPCS work — the cylinder touches a central meridian, not the equator.

Anchor Type

visual_association

Why It Works

A culturally familiar Filipino object (San Miguel can) serves as a concrete 3D visualization. The contrast between upright (Mercator) and tipped (Transverse Mercator) makes the geometric difference immediately clear.

Example Usage

Question: 'How does Transverse Mercator differ from the standard Mercator projection?' Recall the tipped can → TM has the cylinder axis perpendicular to the polar axis, tangent along a meridian rather than the equator.

Recall Trigger

San Miguel can tipped on its side pressing against a meridian

Topic

Scale Factor

Concept

Scale factor k = projected distance / true ellipsoidal distance

Anchor Id

Difficulty

medium

Memory Aid

Think of k as a **PAD factor** — how much the Projection has Added or Deducted from the true ground distance. If k = 1.00012, the grid distance is 0.012% LONGER than reality (stretched). If k = 0.99960, the grid is 0.040% SHORTER (compressed). The formula is just a ratio: how many meters did the map claim per meter on the ground? A photocopy machine analogy: k is the zoom level — 100% means no change (k=1), 99.96% means slightly shrunk (k=0.9996).

Anchor Type

analogy

Why It Works

The photocopy machine is a universally familiar technology in Filipino offices and universities. Zoom percentages directly correspond to scale factor values, making the abstract ratio concrete.

Example Usage

Question: 'A line measures 5000.00 m on the ellipsoid. If k = 0.99960, what is the grid distance?' Recall photocopy zoom → Grid = k × ellipsoidal = 0.99960 × 5000.00 = 4998.00 m (the photocopy came out slightly smaller).

Recall Trigger

Photocopy machine zoom percentage

Topic

UTM Scale Factor

Concept

UTM uses k₀ = 0.9996 at the central meridian (less than 1, not equal to 1)

Anchor Id

Difficulty

medium

Memory Aid

Surveyor Mang Ben is laying out a highway along the UTM central meridian. He notices his grid distances are consistently SHORTER than the ellipsoidal distances. His professor explains: 'The UTM designers deliberately set k₀ = 0.9996 — just 4 parts per 10,000 less than 1 — so the scale error is balanced across the zone. Near the central meridian, you're UNDER true scale; at the zone edges, you're OVER true scale. It averages out.' Mang Ben remembers: '0.9996 — four short of the perfect 10,000.'

Anchor Type

micro_story

Why It Works

The highway surveyor narrative gives a professional context. The phrase 'four short of the perfect 10,000' (i.e., 10000 - 4 = 9996) provides a numerical hook that embeds the exact value 0.9996.

Example Usage

Question: 'What is the scale factor at the central meridian of a UTM zone?' Recall Mang Ben's 'four short' → k₀ = 0.9996 (less than 1; grid distances near the central meridian are slightly shorter than ellipsoidal).

Recall Trigger

'Four short of the perfect 10,000' → 9996 → k₀ = 0.9996

Topic

Scale Factor Variation

Concept

Scale factor is less than 1 at the central meridian, greater than 1 at zone edges (UTM/TM)

Anchor Id

Difficulty

medium

Memory Aid

Chant this to the tune of a simple Filipino counting song: **'Sa gitna, maikli (at the center, it's short) — k less than one! Sa gilid, mahaba (at the edges, it's long) — k more than one! Sa standard line, tama (on the standard line, it's exact) — k equals one!'** (Center short, Edge long, Standard line — just right.)

Anchor Type

rhyme

Why It Works

Rhyme and rhythm engage the phonological loop in working memory, encoding information through sound as well as meaning. Switching to Tagalog mid-chant creates a pattern-break that enhances memorability.

Example Usage

Question: 'Describe how scale factor varies across a UTM zone.' Recall the chant → k < 1 at central meridian, k > 1 at zone edges, k = 1 at the two standard lines (secant cylinder).

Recall Trigger

Chant: 'Sa gitna maikli, sa gilid mahaba'

Topic

Scale Factor Formula

Concept

Grid distance = k × ellipsoidal distance

Anchor Id

A10

Difficulty

easy

Memory Aid

Remember: **'Grid Gets k-times Ground'** — the three G's plus k. Grid (projected) distance equals k multiplied by Ground (ellipsoidal) distance. The phrase flows naturally: 'The Grid Gets k-times the Ground measurement.' Write it as: G = k × G₀ (Grid = k × Ground). The alliteration of three G's locks in the formula structure.

Anchor Type

mnemonic

Why It Works

Alliteration is one of the most powerful phonological memory aids. 'Grid Gets k-times Ground' encodes the variable names AND the multiplication operation in a single five-word phrase.

Example Usage

Question: 'An ellipsoidal line is 8000 m; k = 1.00012. Find the grid distance.' Recall 'Grid Gets k-times Ground' → Grid = 1.00012 × 8000 = 8000.96 m.

Recall Trigger

The three G's: 'Grid Gets k-times Ground'

Topic

PPCS and Philippine Reference System

Concept

Philippine Plane Coordinate System (PPCS) — based on Transverse Mercator, uses PRS92

Anchor Id

A11

Difficulty

medium

Memory Aid

Think of the PPCS as the Philippines' own national ID system for coordinates. Just as every Filipino has a PhilSys ID tied to a national database (PSA), every surveyed point in the Philippines has a PPCS coordinate tied to PRS92 (Philippine Reference System 1992). The PPCS uses Transverse Mercator — the national coordinate 'format' — and PRS92 is the 'database' (reference ellipsoid/datum) it connects to. Without PRS92, PPCS coordinates are like an ID card with no database behind it.

Anchor Type

micro_story

Why It Works

Linking a technical system (PPCS/PRS92) to the universally known PhilSys national ID creates an immediate, emotionally resonant connection. The database/card analogy clarifies the projection vs. datum distinction.

Example Usage

Question: 'What coordinate system and projection does the Philippines officially use for cadastral surveys?' Recall the PhilSys analogy → PPCS (Transverse Mercator based, referenced to PRS92), established under RA 8560 governing geodetic engineering practice.

Recall Trigger

PhilSys ID card (PPCS) connected to PSA database (PRS92)

Topic

Mercator Projection

Concept

Mercator projection — cylindrical, conformal; distorts area badly at high latitudes (Greenland effect)

Anchor Id

A12

Difficulty

easy

Memory Aid

Mercator is like a strict but unfair classroom grader: it gives PERFECT SCORES (correct angles) to students near the equator (the passing line), but it INFLATES the grades of students near the poles so badly that tiny Greenland looks bigger than Africa on the final grade sheet — even though Africa is actually 14× larger. Mercator is 'conformally honest' about angles but 'inflates' area as you move poleward.

Anchor Type

analogy

Why It Works

The grade inflation analogy connects to a universally stressful Filipino student experience. The Greenland-Africa fact is a famous, shocking cartographic example that reinforces the concept through cognitive dissonance.

Example Usage

Question: 'Classify Mercator by developable surface and preserved property.' Recall the grade inflation teacher → Cylindrical (cylinder surface), Conformal (preserves angles/shape). Note: area is NOT preserved — Greenland effect.

Recall Trigger

Grade inflation at the poles — Greenland looks bigger than Africa

Topic

Equidistant Projections

Concept

Equidistant projection preserves distance along certain lines (not all distances)

Anchor Id

A13

Difficulty

medium

Memory Aid

An equidistant projection is like a jeepney route map — it shows the CORRECT DISTANCE along specific routes (the standard lines), but distances off-route (between non-standard points) are approximate. Just as the jeepney fare matrix is accurate only along designated routes, equidistant projections are accurate only along designated standard lines or from a specific center point.

Anchor Type

analogy

Why It Works

The jeepney fare matrix is a familiar, daily-life reference for Filipino students. The 'along the route' limitation of fare accuracy perfectly mirrors the 'along certain lines only' limitation of equidistant projections.

Example Usage

Question: 'Which projection property is appropriate for an air-navigation chart?' Recall the jeepney route — navigation needs correct distances along specific routes → Equidistant projection (preserves distance along standard lines, useful for plotting flight paths from a central airport).

Recall Trigger

Jeepney fare matrix — correct only along the route

Topic

Standard Line and Scale Factor

Concept

Standard line = line of zero distortion (k = 1) on a projection

Anchor Id

A14

Difficulty

easy

Memory Aid

Visualize the standard line as the EQUATOR LINE on a basketball court — the painted line is perfectly flat, no warping, no stretching. This is where k = 1 exactly. Step off the painted line toward either basket (toward the zone edges), and the floor material starts to warp under you (k moves away from 1). The standard line is the only place the map 'touches' the real Earth perfectly.

Anchor Type

visual_association

Why It Works

The basketball court centerline is a vivid spatial image. The 'warping floor' image physically represents scale distortion increasing with distance from the standard line — an embodied cognition technique.

Example Usage

Question: 'Where does k = 1 on a Transverse Mercator projection?' Recall the basketball court line → k = 1 on the standard line(s). For UTM, there are two standard lines (secant cylinder) on either side of the central meridian.

Recall Trigger

Basketball court centerline — perfectly flat, k = 1 exactly

Topic

Projection Properties Mutual Exclusivity

Concept

Conformal ≠ Equal-area — a projection CANNOT be both simultaneously

Anchor Id

A15

Difficulty

hard

Memory Aid

Two engineers, Connie (Conformal) and Erica (Equal-area), apply for the same job at NAMRIA. The hiring manager says: 'The law requires you can't both work the same project.' Connie saves angles perfectly but stretches Greenland. Erica compresses everything to save areas but distorts shapes. They are mutually exclusive — you hire one, you lose the other. This is a fundamental theorem of differential geometry: no projection can be both conformal and equal-area.

Anchor Type

micro_story

Why It Works

Personifying projections as job applicants creates a narrative with conflict and resolution. The mutual exclusivity becomes a 'law' enforced by NAMRIA (a real Philippine agency), grounding the abstract theorem in professional reality.

Example Usage

Question: 'Can a projection be both conformal and equal-area?' Recall the NAMRIA hiring — No. They are mutually exclusive. A conformal projection (preserves angles) cannot simultaneously preserve area, and vice versa.

Recall Trigger

Connie vs. Erica at the NAMRIA interview — only one gets hired

Topic

Azimuthal Projection

Concept

Azimuthal (planar) projection — flat plane tangent to the globe; best for polar regions

Anchor Id

A16

Difficulty

easy

Memory Aid

Picture a giant PIZZA BOX lid pressed flat against the North Pole of a globe. The pizza box is the azimuthal plane — flat, tangent at the pole. Everything radiates outward from the pole like slices of pizza. The center (pole) has k = 1 (perfect contact), but the crust (outer edges) gets stretched. The pizza analogy also explains why azimuthal projections work best for CIRCULAR areas (polar regions look like a round pizza).

Anchor Type

visual_association

Why It Works

Pizza is universally beloved and familiar. The circular, radiating geometry of a pizza perfectly represents the azimuthal grid structure. The 'crust stretching' humorously encodes edge distortion.

Example Usage

Question: 'Which developable surface is used in an azimuthal projection, and for which regions is it most suitable?' Recall the pizza box → Flat plane (planar) tangent to the globe; best for polar regions (circular coverage around a pole).

Recall Trigger

Pizza box lid pressed on the North Pole

Topic

Conic Projection

Concept

Conic projection — cone placed over the globe; best for mid-latitude regions

Anchor Id

A17

Difficulty

easy

Memory Aid

A conic projection is like placing a party hat (cone) over the globe. The hat sits best over the middle latitudes — it perches naturally around the temperate zones, touching along a circle of latitude (the standard parallel). It fits poorly at the equator (hat falls off) and at the poles (hat crushes flat). This is why conic projections are chosen for countries in mid-latitudes, and why the Albers Equal-Area Conic is used for continental USA (not the Philippines, which is near the equator).

Anchor Type

analogy

Why It Works

Party hats are festive and vivid. The physical behavior of placing a cone on a sphere (where it naturally contacts mid-latitudes) embeds the geographic suitability rule through direct analogy.

Example Usage

Question: 'For which latitude region is a conic projection most suitable?' Recall the party hat → Mid-latitudes (temperate zones). The Philippines, being near the equator, uses cylindrical (TM) projections instead.

Recall Trigger

Party hat perching naturally around the middle latitudes of a globe

Topic

UTM Secant Cylinder

Concept

Why UTM uses secant cylinder (two standard lines) instead of tangent cylinder

Anchor Id

A18

Difficulty

hard

Memory Aid

Imagine slicing a round bibingka into strips. A tangent cut (one line of contact) makes one strip perfect but the edges burn. A secant cut (two lines of contact, slightly inside the crust) gives you a wider strip where the whole piece is 'almost perfect' — slight undercooking at the center, slight overcooking at the edges, but nothing extreme. UTM's k₀ = 0.9996 is the 'secant slice' — the cylinder cuts slightly INSIDE the globe at two standard lines, balancing the scale error across the zone width.

Anchor Type

analogy

Why It Works

Bibingka (Filipino rice cake baked in a clay pot) is a culturally rich food analogy. The baking metaphor of 'just right' cooking across the strip embeds the concept of balanced error distribution.

Example Usage

Question: 'Why does UTM use a scale factor of 0.9996 at the central meridian rather than 1.0000?' Recall the bibingka secant cut → A secant cylinder (k₀ = 0.9996) creates two standard lines (k=1) within the zone, minimizing the maximum scale error across the 6° zone width. A tangent cylinder (k₀=1.0000) would give larger errors at the edges.

Recall Trigger

Bibingka sliced with a secant cut — balanced baking across the strip

Topic

PPCS Zones

Concept

PPCS zones in the Philippines — 5 TM zones covering the archipelago

Anchor Id

A19

Difficulty

medium

Memory Aid

The Philippines has **5 PPCS zones** — remember '**5 fingers on one hand**.' Each finger represents one zone, and your hand (the Philippines) is covered completely. The zones are numbered I through V (Roman numerals 1–5) from west to east, each with its own central meridian spaced at regular intervals. One hand, five fingers, five zones — no finger (zone) left behind.

Anchor Type

mnemonic

Why It Works

The hand analogy provides a spatial, embodied reference. Spreading five fingers visually mimics the arrangement of five zones across the archipelago. The phrase 'no finger left behind' adds a humor hook.

Example Usage

Question: 'How many TM zones does the PPCS have for the Philippines?' Recall five fingers → 5 PPCS zones (I–V), each using Transverse Mercator with a specific central meridian referenced to PRS92.

Recall Trigger

Five fingers on one hand = five PPCS zones

Topic

Conformal Projection for Surveying

Concept

Conformal projection essential for surveying — angles/bearings transfer correctly to grid

Anchor Id

A20

Difficulty

medium

Memory Aid

Surveyor Ate Liza is running a traverse in Davao City using a total station. She measures angles meticulously to 5-second precision. Back in the office, she plots onto the PPCS grid (Transverse Mercator). Her supervisor tells her: 'The reason your field angles plot correctly on this grid without angular correction is because TM is conformal — angles on the ground equal angles on the map locally.' If TM were NOT conformal, every bearing would need a distortion correction, making traverse computation an accounting nightmare.

Anchor Type

micro_story

Why It Works

A relatable professional scenario (traverse surveying in a known Philippine city) makes the abstract property practically tangible. The 'accounting nightmare' metaphor emphasizes WHY conformality matters to engineers.

Example Usage

Question: 'Explain why survey grids like UTM and PPCS use a conformal (Transverse Mercator) projection.' Recall Ate Liza → Conformal projections preserve angles locally, so field-measured bearings and traverse angles transfer directly to the grid with minimal angular distortion — essential for surveying accuracy.

Recall Trigger

Ate Liza's traverse in Davao — angles match the grid without correction

Revision Game

The impossibility of projecting a curved surface onto a flat plane without distortion

Clue

I am the Filipino fruit whose peel, when flattened, always tears or stretches somewhere. I represent the fundamental impossibility of perfect map projection. What concept am I?

Memory Link

A1 — Lansones peel analogy

CEE — Conformal (angles/shape), Equal-area (area), Equidistant (distance)

Clue

I am a three-letter shout of surprise in Filipino. My letters stand for the three properties a map projection can preserve. What am I, and what do my letters stand for?

Memory Link

A2 — CEE acronym

k₀ = 0.9996

Clue

Engineer Mang Ben said I am 'four short of the perfect 10,000.' I am the scale factor at the central meridian of every UTM zone. What is my exact value?

Memory Link

A8 — 'Four short of the perfect 10,000' micro-story

Transverse Mercator (TM) — horizontal cylinder tangent to a central meridian

Clue

I am a San Miguel Beer can tipped on its side, pressing against a meridian of the globe. I am the geometric setup of which projection?

Memory Link

A6 — San Miguel can visual association

A projection cannot be simultaneously conformal (angle-preserving) and equal-area — they are mutually exclusive

Clue

Connie and Erica both applied for the same NAMRIA job but the law says only one can be hired per project. I am the mathematical theorem they represent. State it.

Memory Link

A15 — Connie vs. Erica at NAMRIA micro-story

'Grid Gets k-times Ground' → Grid distance = k × Ellipsoidal distance

Clue

I am three words — each starting with G — that encode the most important formula in this chapter. Recite me and write the formula I represent.

Memory Link

A10 — three G's mnemonic

The secant cylinder in UTM — cutting slightly inside the globe creates two standard lines (k=1), balancing scale error across the 6° zone and minimizing maximum distortion

Clue

I am a Filipino dessert baked in a clay pot, sliced with a secant cut rather than a tangent cut. By analogy, I explain why UTM uses k₀ = 0.9996 instead of 1.0000. What concept am I illustrating?

Memory Link

A18 — Bibingka secant cut analogy

ID card = PPCS (Philippine Plane Coordinate System); Database = PRS92 (Philippine Reference System 1992)

Clue

I am a Philippine national ID card (PhilSys) connected to a PSA database. In geodetic engineering, the ID card is the ___ and the database is the ___. Fill in the blanks.

Memory Link

A11 — PhilSys analogy for PPCS/PRS92

Ellipsoidal distance = true ground distance in metres; Grid distance = the projected/map distance measured in metres; k = scale factor. Division by k 'undoes' the projection scaling to recover the true ellipsoidal distance.

WGS84 — global geocentric datum (used for GPS raw output)
PRS92 — Philippine Reference System 1992 (national geodetic datum, referenced to GRS80 ellipsoid)
PPCS — Philippine Plane Coordinate System (TM-based 2D grid, referenced to PRS92)
UTM — Universal Transverse Mercator (global TM grid, 6° zones, also compatible with Philippine work)

Loading diagram…

Previous chapter

Stereoscopy, DEM and Orthophoto

Next chapter

Philippine Plane Coordinate System and UTM

Ready to practise for the GELE 2026?

Super Tutor's AI review plan adapts to your weak areas and builds a weekly practice schedule around your target GELE exam date.

Start free See the full GELE guide GELE preparation guide

← Back to Photogrammetry & Cartography hub

GELE Photogrammetry & Cartography — Map ProjectionsMemory Anchors

Exam context

Map Projections - Memory Anchors

Anchors

Tags

Topic

Concept

Anchor Id

Difficulty

Memory Aid

Anchor Type

Why It Works

Example Usage

Recall Trigger

Tags

Topic

Concept

Anchor Id

Difficulty

Memory Aid

Anchor Type

Why It Works

Example Usage

Recall Trigger

Tags

Topic

Concept

Anchor Id

Difficulty

Memory Aid

Anchor Type

Why It Works

Example Usage

Recall Trigger

Tags

Topic

Concept

Anchor Id

Difficulty

Memory Aid

Anchor Type

Why It Works

Example Usage

Recall Trigger

Tags

Topic

Concept

Anchor Id

Difficulty

Memory Aid

Anchor Type

Why It Works

Example Usage

Recall Trigger

Tags

Topic

Concept

Anchor Id

Difficulty

Memory Aid

Anchor Type

Why It Works

Example Usage

Recall Trigger

Tags

Topic

Concept

Anchor Id

Difficulty

Memory Aid

Anchor Type

Why It Works

Example Usage

Recall Trigger

Tags

Topic

Concept

Anchor Id

Difficulty

Memory Aid