Glossary
2D Layers / 3D Layers — the headings a scene's Contents sorts layers under: flat layers drawn on the ground, and layers that stand up from it.11
absolute path — a path that starts at the drive letter and names every folder down to the data.2
add-in — a package that extends ArcGIS Pro with new buttons and panes, installed from an .esriAddinX file.0
adjacency — features meeting along a boundary without overlapping.6
alias — a readable label shown in place of a field's name.5
API key — a secret string that identifies you to a provider; treat it like a password.0
.aprx — the project file you open; it stores maps, layouts and connections, and points at data rather than containing it.0
ArcGIS Online — Esri's cloud platform where maps, apps and data are shared, reached in Pro through the Portal tab.2
Ask mode — Waldo reads and explains your project but cannot change it; every lesson runs in Ask.0
aspect — the compass direction a slope faces, 0° to 360° from north, −1 for flat cells.8
attribute — a value describing a feature, stored in one field of its row.1
attribute query — a query that selects records by their attribute values, written as an SQL WHERE clause.6
attribute table— one row per feature, one column per field.1— the table tied to a layer, with one row per feature.5
azimuthal — preserving true directions from a centre point; can also be conformal, equal-area or equidistant.3
band— one layer of values in a raster; a land-cover map has one, a colour image has several.2— one layer of values in a raster; a multiband image such as Landsat holds several per cell.8
basemap — the reference layers at the bottom of a map that give it context.1
bookmark — a saved extent (in a scene, a saved camera) that a view can return to by name.1
Boolean raster — a raster of 1 (true) and 0 (false) cells, the answer to a condition asked of every cell.8
box plot — a chart of a distribution's median, quartiles and range, suited to comparing groups.6
broken link — a layer whose data can no longer be found at its stored path, marked with a red exclamation mark and repaired from the Source tab.2
buffer — a polygon covering every place within a given distance of a feature.7
Calculate Field — a tool that fills a field from an expression over each row's other fields.5
Calculate Geometry — a tool that fills a field with each feature's area, length, perimeter or coordinates.5
camera pitch — how far a scene's camera looks down from the horizon: −90° straight down, 0° level.11
cardinality — how many rows one key value matches on each side of a join: one-to-one, many-to-one, one-to-many or many-to-many.5
cartography — the art and science of designing maps.4
case field — the field whose values define the groups, one output row per value, in a summary.6
cell (pixel)— one square of a raster grid; its size sets the smallest thing the raster can show.2— one square of a raster, standing for one square of ground and holding one value.8
cell size (spatial resolution) — the ground length of one cell's side; nothing smaller than a cell exists in the raster.8
checkpoint — the check at the end of a lesson step, made by reading your actual project.0
choropleth map — a map of areas shaded by class of a rate or proportion (Graduated Colors in Pro).4
classification — grouping features into a few classes by attribute value, with a stated method.4
clip — keeps the parts of the input features inside a boundary; the input's attributes are unchanged.7
colorizer — the rule that draws a raster: unique values, stretch, classify or RGB.8
compromise projection — a projection that keeps no property exactly but every distortion moderate, such as Robinson or Winkel Tripel.3
conformal — preserving local angles, so small shapes are true; areas are distorted.3
construction tool — the tool that turns clicks into a shape, such as Line, Arc, Polygon or Rectangle.10
contextual tab — a ribbon tab that appears only while something that needs it is selected.1
cross-validation — testing an interpolation by leaving out each sample in turn, predicting its value from the others and comparing the prediction with the measurement.9
data source — the path or web address a layer uses to find its data, shown on the layer's Source tab.2
datum — the ellipsoid and its position relative to the Earth, which give latitude and longitude a definite meaning; local datums fit one region, geocentric ones the whole Earth.3
definition query — a layer filter that hides the features failing a test, without changing the stored data.6
destination / source table — in a join, the table that is added to / the table whose columns are added.5
developable surface — a cylinder, cone or plane: a surface that unrolls flat without stretching, used to build and classify projections.3
digital elevation model (DEM) — a raster of ground heights.8
dissolve — merging the features of one layer that share a field value, keeping that field and any requested statistics.7
dissolve (buffer option) — merging overlapping buffer polygons into one feature so that no area is counted twice.7
distance decay — the weakening of a relationship or an influence as distance grows.9
Do mode — Waldo can act on your project: run tools, change symbology, build layouts.0
domain — a list or range of allowed values for a field, offered as a pick list when editing.10
draping — drawing a flat layer on the ground surface of a scene, so that it follows the terrain.11
drawing order — the order of layers in the Contents pane; a layer higher in the list draws on top.1
dynamic label / annotation — text placed automatically from a field; text placed and stored piece by piece.4
ecological fallacy — the mistake of assuming that what is true of an area on average is true of the individuals in it.4
ellipsoid (spheroid) — the smooth shape made by rotating an ellipse about its shorter axis; the mathematical model of the Earth, defined by its two semi-axes.3
equal interval — a classification method that divides the range into classes of equal width.4
equal-area — preserving the relative sizes of areas everywhere; shapes are distorted.3
equidistant — preserving true scale along certain lines, such as from one or two points to all others.3
erase — keeps the parts of the input features outside a boundary; the input's attributes are unchanged.7
extent — the rectangle of the map shown in a view at a given moment.1
Extract by Mask — a tool that keeps a raster's cells inside a polygon or raster mask and sets the rest to NoData.8
Extract Values to Points — a tool that writes the value of the cell under each point into the point's table.8
extrusion — drawing each feature pushed up by a height into a solid (point to column, line to wall, polygon to block); a display setting, not a change to the data.11
false-colour composite — an image with bands other than red, green and blue sent to the screen's colours, such as near infrared into red.8
feature — one point, line or polygon in a layer, together with its row of attributes.1
feature class— a table in a geodatabase whose shape field holds point, line or polygon geometry.2— a set of features of one geometry type, with the same fields and coordinate system, stored in a geodatabase.10
feature dataset — a group of feature classes in a geodatabase that share one coordinate system.2
feature layer — a web layer that serves features and attributes that can be queried and, when the publisher allows it, copied.2
feature template — a recipe for new features: the target layer, its symbol, its construction tools and default attribute values.10
FID_ column — a column an overlay adds to record which feature of an input each piece came from; −1 means none.7
field — one column of a table: one attribute of every record, with a name, a type and a definition.5
field length — the number of characters a Text field can hold.5
figure-ground — the contrast that separates a map's subject from its background.4
file geodatabase — Pro's container for data, stored as a folder ending in .gdb and managed through Pro.2
flattening — f = 1 − b/a, how much shorter the polar radius is than the equatorial; about 1/298 for the Earth, shown in dialogs as its inverse, 1/f.3
Float / Double — decimal storage types keeping six or seven and about fifteen significant digits.5
floating-point raster — a raster of decimal values, usually measurements such as elevation; it has statistics instead of a table.8
folder connection — a shortcut in the Catalog pane to a folder on disk, the way downloaded data reaches a map.2
generalization — selecting, simplifying, classifying and symbolizing geographic information so it can be shown at a given scale and for a given purpose.4
geodatabase — a container for GIS data (feature classes, tables, rasters); a file geodatabase is a .gdb folder that Pro shows as one item.0
geodesic — the shortest path between two points along the curved surface of the ellipsoid; geodesic measurement ignores the map's projection.3
geographic coordinate system (GCS) — latitude and longitude in degrees, defined by a datum, a prime meridian and an angular unit.3
geographic transformation — a calculation that moves coordinates from one datum to another, such as NAD 1927 to NAD 1983, so that data line up.3
geoid — the irregular surface of equal gravity potential that mean sea level follows; the reference for heights, within about ±100 m of the ellipsoid.3
GeoJSON — a plain-text format for features built on JSON, an IETF standard since 2016.2
geometry type — point, line or polygon; fixed when the feature class is created.10
geoprocessing environment — a setting applied around a tool, such as the processing extent.7
global scene — a scene of the whole round Earth, for large areas where the Earth's curvature matters.11
graduated / proportional symbols — point symbols sized by class; point symbols sized in exact proportion to each value.4
graticule — the network of meridians and parallels drawn on a globe or a map.3
ground — the elevation surface a scene stands on, built from one or more DEMs.11
halo — a light outline around lettering that separates it from a busy background.4
heading — the compass direction a scene's camera faces, counted clockwise from north: 0° north, 90° east, 180° south, 270° west.11
heads-up digitizing — tracing features on screen by clicking their vertices over an image.10
hillshade — a raster of the brightness each cell would have under a lamp at a set direction and height.8
histogram— a chart of how many features have each value.4— a chart of one numeric field's distribution, as counts in value bins.6
hue / saturation / value — which colour; how pure versus greyed; how light or dark.4
identity — an overlay that keeps the first input's footprint, split wherever the second input covers it.7
imagery layer — a raster served live from a server.2
IN — an SQL operator that tests a field against a list of values.6
integer raster — a raster of whole numbers, usually codes such as land-cover classes; it can have an attribute table.8
interpolation — estimating values at unsampled places from nearby sample points, usually into a raster.9
intersect — an overlay that keeps only the pieces lying in both inputs, each carrying both inputs' attributes.7
interval / ratio — quantities whose zero is arbitrary / quantities with a true zero, where twice the number means twice as much.5
inverse distance weighting (IDW) — interpolation by a weighted average of nearby samples, each weight one over the distance to a power.9
Irish Transverse Mercator (ITM) — Ireland's national grid (EPSG 2157): transverse Mercator on IRENET95, central meridian 8° W, scale factor 0.99982, false origin 600,000 m E, 750,000 m N.3
isohyet — a line joining places of equal rainfall; the rain version of an elevation contour.9
join — attaching the columns of a source table to the rows of a destination table through a key field.5
kernel density — a surface made by spreading each point into a hill of a chosen radius and adding the hills, giving points per unit of area.9
key field — a field in both tables whose values match a row on one side to a row on the other.5
KML — an XML format for geographic display that began with Google Earth and is now an OGC standard.2
kriging — a statistical interpolation method that fits its weights to how similarity falls off with distance and also estimates its own uncertainty (named only).9
large scale / small scale — a large-scale map (1:10,000) shows a small area in detail; a small-scale map (1:1,000,000) a large area with little detail.3
layer— one dataset drawn in a map with its own name and symbology; the data stays where it is.1— a map's reference to a dataset together with its name, symbology and other drawing settings.2
layout— a page in a project that arranges maps and map elements for printing or export.1— a fixed-size page holding map frames and map elements.4
Learn panel — the list of every module and lesson in the Waldo pane, with your progress marked and Start, Resume and Check my work buttons.0
legibility / harmony — whether text can be read; one or two typefaces used consistently.4
lesson — a short sequence of steps, done in Pro, that teaches one idea.0
level of measurement — whether values are nominal, ordinal, interval or ratio, which determines the arithmetic that makes sense.5
LIKE — an SQL operator that matches text against a pattern, with % standing for any run of characters.6
Living Atlas— Esri's curated collection of ready-to-use layers, reached from the Portal tab.1— Esri's curated collection of maps and data, in public, subscriber and premium tiers.2
local scene — a scene of a flat piece of the world in a projected coordinate system, for a site, a town or a mountain.11
M value / Z value — an optional measure (for routes) or height stored with each vertex.10
map — a project item holding layers drawn in two dimensions.1
map algebra — arithmetic and comparisons applied to rasters cell by cell, each writing a new raster.8
map projection — a mathematical transformation of the curved Earth onto a plane; it always distorts shape, area, distance or direction somewhere.3
mask — a setting that limits a raster tool's output to the cells inside a study-area polygon.9
Max Height — the extrusion type that puts a flat top at the given height above the highest ground under each feature.11
merge / append — combining feature classes of the same type into a new one (merge) or into an existing one (append), without splitting; overlaps become duplicate features.7
metadata — data about data: who made it, what it is, when, where, how and why.2
modifiable areal unit problem — the way a mapped pattern can change when the same data are summarized over differently drawn areas.4
module — a group of lessons on one topic; the course has twelve, numbered 0 to 11.0
multipart feature — one feature, one row, made of several separate shapes.7
multiple ring buffer — buffers at several distances around the same features, stored as non-overlapping rings or overlapping disks.7
natural breaks (Jenks) — a classification method that places breaks where the data thin out, keeping each class's values alike.4
neatline — an optional line enclosing the map or the whole layout.4
NoData — a cell that holds no value, such as a cell outside the mask of an extraction.8
node — the first (start) or last (end) vertex of a line; lines that meet should share one.10
nominal / ordinal — values that are names or categories / categories with a meaningful order.5
normalization — dividing a count by another field, such as area or population, to make a rate.4
null — an empty field value, which records that nothing is known and is not the same as zero.5
OBJECTID — the unique number a geodatabase keeps for every row of a table.5
on-the-fly projection — the software's redrawing of every layer in the map's coordinate system at display time, without changing the stored data.3
optical centre — the point a little above the geometric centre of a page where the eye first lands.4
orbit — moving a scene's camera in a circle round a point while it keeps facing the point.11
overlay — combining two feature classes by location into a new feature class.7
pane — a dockable window inside ArcGIS Pro, such as Contents, Catalog or Waldo.0
planar — measured with flat geometry in a projected coordinate system, so only as accurate as that projection is where you measure.3
population density — people per unit of area; a rate, suited to a choropleth where a count is not.5
pop-up — the window that shows one feature's attributes when the feature is clicked.1
power (IDW) — the exponent that sets how fast a sample's weight falls with distance; 2 by default.9
project — an ArcGIS Pro workspace: a folder holding the .aprx file, a default geodatabase, a toolbox and housekeeping folders.0
project (.aprx) — the Pro file that holds maps, layouts and connections and a pointer to each layer's data, but not the data itself.2
projected coordinate system (PCS) — a GCS plus a map projection and a linear unit, giving flat x and y coordinates in metres or feet.3
provider — the company or program that runs the language model Waldo uses.0
qualitative / sequential / diverging scheme — distinct hues for categories; an ordered light-to-dark run for amounts; two hues meeting at a pale middle for amounts with a meaningful midpoint.4
qualitative attribute — an attribute that tells kinds of things apart: a category, a name, a code.4
quantile — a classification method that puts the same number of features in every class.4
quantitative attribute — an attribute that measures an amount: a count, an area, a rate, a percentage.4
R² — the share of the variation in the vertical-axis variable that the fitted line accounts for, from 0 (none) to 1 (all).6
raster— a layer made of a regular grid of cells, each holding one value.1— a data model that covers the ground with a grid of equal cells in rows and columns, each holding one value.2— a grid of equal cells in rows and columns covering an area, each cell holding one value.8
raster attribute table— an integer raster's table: one row per distinct cell VALUE, with a COUNT of the cells that hold it.5— one row per cell value of an integer raster, with the fields Value and Count and any added columns.8
Raster Calculator — ArcGIS Pro's tool for map-algebra expressions, with quoted raster names and strict operators.8
Raster to Polygon — a tool that turns groups of equal integer cells into polygons, one row per polygon.8
Reclassify — a tool that replaces values or ranges of values with new values; its output is always integer.8
record — one row of a table; in an attribute table, one feature.5
reference map — a map of where things are, with many features at roughly equal weight, for many purposes.4
relate — a link between two tables that keeps them separate instead of merging their columns.5
relative path — a path written from the folder that holds the project file, so the project folder can move as a whole.2
relief map — a DEM in an elevation colour scheme drawn partly transparent over its own hillshade.8
representative fraction (RF) — a map scale written as 1:n, one unit on the map for n of the same unit on the ground.3
reshape / merge / split — redrawing part of a feature's edge; making one feature of several; cutting one feature into two.10
ribbon — the band of tabs across the top of Pro, each holding groups of commands.1
save edits — writing the edits made since the last save into the geodatabase; separate from saving the project.10
scale factor — the actual scale at a point of a projected map divided by the stated scale; 1 on the standard lines.3
scatter plot — a chart of two numeric fields, one point per feature, for reading their relationship.6
scene— a project item that draws layers in 3D, seen through a camera that tilts and turns.1— a map drawn in three dimensions, with a ground surface, flat layers draped on it and features that can stand up from it.11
search neighbourhood — the samples an estimate may use: a set number of the nearest, or all within a set radius.9
search radius — in kernel density, the distance at which each point's hill falls to zero; the setting that most changes the map.9
segment — the straight piece of a line or polygon boundary between two consecutive vertices.10
selection — the features currently highlighted, shown on the map, in the table and in the count; replaced by the next new query.6
selection type — how a new query combines with the current selection: new, add (OR), remove (NOT), subset (AND), switch or clear.6
sentinel value — a code such as −9999 stored in place of a missing measurement; it must be removed before any calculation.9
service URL — the web address of one published layer, which can be added to a map directly.1
shapefile — an older vector format stored as a family of same-named files (.shp, .shx, .dbf and optional others) that must be kept together.2
Short / Long — whole-number storage types, up to 32,767 and up to about 2.1 billion.5
site-selection model — a chain of spatial operations that keeps only the places meeting every written criterion.7
sketch — the shape being drawn, before finishing turns it into a feature.10
skewed distribution — values piled at one end with a long tail at the other.4
slope — the steepest rate of change of height from a cell to its neighbours, in degrees or percent.8
snap raster — an environment that aligns a new raster's cells exactly with an existing raster's cells.8
snap tolerance — the distance, in pixels or map units, within which snapping pulls the pointer onto a target.10
snapping — moving a vertex exactly onto an end, vertex or edge of another feature when the pointer comes within a tolerance.10
source line — the small text on a finished layout naming the data, the author and the date.11
spatial autocorrelation — the tendency of values at nearby places to be related: alike (positive) or unlike (negative), rather than random.9
spatial data exploration (ESDA) — interactive, iterative questioning of data through linked maps, tables and charts.6
spatial join — attaching one layer's attributes to another's features by their spatial relationship.7
spatial query — a query that selects features by their spatial relationship to other features.6
spatial relationship — the geometric test in a spatial query, such as intersect, within, contains, touches or within a distance.6
SQL — Structured Query Language, the language of relational databases: SELECT fields FROM a table WHERE a test is true.6
standalone table — a table with no geometry, such as a census table or an imported spreadsheet.5
storage type — how a field stores its values: Short, Long, Float, Double, Text, Date or Blob.5
study area — the place a map is about; the data on the map is limited to it.11
suitability analysis — answering "where?" from criteria every cell can pass or fail; the course uses the simplest form, one Boolean raster per criterion, multiplied.8
summarized join — a spatial join that gives each target feature a count or statistic of the join features it matches.7
summary statistics — statistics of a field computed per group of records; the output is always a table.6
symbology — the drawing rules of a layer: its colours, symbols and sizes.1
table (standalone table) — rows and columns with no geometry.2
tangent / secant — a tangent surface touches the globe along one line or at one point; a secant surface cuts it along two standard lines (a plane along one circle).3
target / join features — in a spatial join, the layer that keeps its shapes and rows / the layer that supplies the attributes.7
thematic map — a map of one subject for one purpose, with everything else as context.4
Thiessen (Voronoi) polygons — polygons that assign every location to its nearest sample point; also called proximal zones.9
tile layer / map image layer — a web layer served as a picture of a map, pre-drawn in tiles or drawn by the server on request.2
Tobler's first law of geography — "everything is related to everything else, but near things are more related than distant things" (Waldo Tobler, 1970).9
transformation — an analysis operation that reads existing layers and writes a new feature class, leaving the inputs as they were (Append, which adds to an existing dataset, is the exception).7
undershoot / overshoot — a line that stops short of the line it should meet, or crosses past it.10
undo / discard — taking back the last edit, or every edit since the last save.10
union — an overlay that keeps every piece of both inputs, each piece carrying both inputs' attributes.7
UTM (Universal Transverse Mercator) — 60 transverse Mercator zones, each 6° wide, with a central-meridian scale factor of 0.9996 and coordinates in metres.3
vector — a data model that represents features as points, lines and polygons built from coordinates, with one row of attributes per feature.2
vertex— one stored coordinate pair along a line or a polygon's boundary; straight segments join the vertices.2— one x, y coordinate of a line or polygon; the shape is the list of its vertices.10
vertical exaggeration — a factor that multiplies every height of the ground; 2 doubles the relief, 1 shows it true.11
view — a work area showing a map, layout, scene or table; one view is active.1
visual hierarchy — design that makes the most important elements the most prominent.4
visual variable — a graphic property of a symbol, such as size, weight, shape, orientation, texture, hue, value or saturation, that the eye reads as a difference.4
Web Mercator — the spherical Mercator formula applied to WGS 84 coordinates (EPSG 3857); the system of most web basemaps, stretching lengths by 1/cos(latitude).3
WHERE clause — the test part of an SQL query: a field, a comparison and a value, joined to others by AND, OR and NOT.6
XY resolution — the fine grid on which a feature class stores its coordinates.10
XY tolerance — how close two coordinates may be before they are treated as the same point.10