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Questions tagged [terminology]

Indicates questions asking about the use and meaning of specific technical words in GIS.

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262 votes
11 answers
154k views

Difference between projection and datum

What is the difference between a projection and a datum?
fmark's user avatar
  • 9,371
114 votes
7 answers
180k views

Differences between DEM, DSM and DTM?

I am listing some of the acronyms used in our work and had to stop to think about whether to list these together or separately: DEM: Digital Elevation Model DSM: Digital Surface Model DTM: Digital ...
blah238's user avatar
  • 35.8k
32 votes
2 answers
4k views

Why do we use the terms “longitude” and “latitude” for a spherical body?

To specify a geographic coordinate we use the terms “longitude” and “latitude”. Far as I know, these terms derive from the Latin latitudo (= breadth) and longitudo (= length). In German we use the ...
Jens's user avatar
  • 6,219
25 votes
15 answers
23k views

How do you explain what GIS is?

Whenever I do a presentation about anything related to GIS, I consider the level of knowledge of GIS of the audience. The worst times are definitely when I need to explain GIS to a group that has ...
21 votes
1 answer
373k views

What is the difference between Vector and Raster data models? [duplicate]

From: http://support.esri.com/en/knowledgebase/GISDictionary/term/vector%20data%20model vector data model: [data models] A representation of the world using points, lines, and polygons. Vector models ...
Aquarius_Girl's user avatar
17 votes
2 answers
23k views

What are LiDAR returns?

Can someone help with an explanation and some references, in order to understand the nature of return pulses within a LiDAR system.
DiegoS's user avatar
  • 179
16 votes
4 answers
23k views

Spatial data? Geodata? Geographic Data? Geospatial data? [closed]

What word indicates spatial data within the geographical and geological domains? In particular, what word is precise enough for a science journal article (i.e., formal prose)? Candidates might include ...
16 votes
3 answers
15k views

What does M-value represent?

I am trying to wrap my ahead around the meaning of the M-value. I read ESRI's dictionary definition here: https://support.esri.com/en/other-resources/gis-dictionary/term/m-value and was not able to ...
NULL.Dude's user avatar
  • 2,131
16 votes
1 answer
15k views

Difference between bounding box, envelope, extent, bounds?

Every time when I create a script to manipulate vector (point, line and polygon) in python I meet this doubt. What is the difference between bounding box (bbox), envelope, extent, bounds?
Diogo Caribé's user avatar
15 votes
4 answers
36k views

What is layer file (*.lyr) in ArcGIS Desktop?

My organization uses *.lyr files consistently as a means for our users to view the data and build their mxds. It works great for our purposes, but we have run into an issue where we don't think the ...
Craig's user avatar
  • 4,580
15 votes
4 answers
729 views

When did the word "geospatial" first come into usage?

For historical reasons, I'm trying to figure out when the term "geospatial" came into use? The earliest usages I can find are from around 1994, but I would be really surprised if it wasn't used ...
robguinness's user avatar
14 votes
1 answer
2k views

What does the ST prefix stand for, e.g. in ST_Polygonize?

I was just curious, and couldn't find any reference to this anywhere - is it Spatial Types? Spatial Topography? Something else?
Brian Burns's user avatar
14 votes
1 answer
2k views

What does context mean in PyQGIS?

When writing PyQGIS scripts, especially processing script and expression function, I come across the term context. I use it, but I don't know what all contexts mean actually. There are also Qgs***...
Kadir Şahbaz's user avatar
13 votes
4 answers
2k views

When should I be calling a 'rectangular grid of pixels' a raster or an image?

Reading through GIS literature, it sometimes feels that authors use the two terms with a specific meaning in mind. I always treat the terms interchangeably. Am I wrong? Read the first line in the ...
Thomas's user avatar
  • 978
12 votes
1 answer
7k views

Raster vs Grid vs Lattice terminology?

I have a question about GIS terminology - what is the difference between grid and raster and grid and lattice - in theory?? I thought, that raster is regular network and value is in the cell and the ...
VilemRousi's user avatar
12 votes
5 answers
658 views

Define the "system" in Geographic Information System

When speaking or writing about GIS all too often the concept in peoples' minds for Geographic Information Systems can be rephrased as "the software for map data". While software is integral to GIS, ...
matt wilkie's user avatar
  • 28.2k
12 votes
2 answers
1k views

How do I describe a special relationship between connected edges?

Consider this simple situation where three edges connect at a node: I’d like to write a succinct and clear description of the relationship between A and B in such a way that differentiates it from ...
andytilia's user avatar
  • 1,835
10 votes
3 answers
10k views

Define "geospatial data" for a non-GIS professional

I realize this is a sort of a subjective question, but I've seen other subjective questions on the site, so I thought it I'd put it out there. A colleague recently had a request for "geospatial data" ...
Zachary's user avatar
  • 6,190
10 votes
3 answers
8k views

Difference between lon and lng [closed]

When browsing the web and documentation I see the abbreviation lon and lng used for the longitude part of geometry. I was wondering if there is any difference between lng and lon.
stUrb's user avatar
  • 2,289
10 votes
2 answers
7k views

What is the difference between Ground Sampling Distance (GSD) and spatial resolution?

In research papers on remote sensing, I see some authors referring to spatial resolution (expressed as pixel/distance) and others to Ground Sampling Distance (GSD) (also expressed as pixel/distance). ...
Sytze's user avatar
  • 761
9 votes
3 answers
282 views

Adjective meaning "of the same resolution and extent"

Is there a word that can be used to describe two or more raster grids having the same resolution and extent? I'm fishing around with words like "coincident" and "coextensive," but nothing feels quite ...
dbaston's user avatar
  • 13.1k
9 votes
2 answers
2k views

Finding Similar Map Paths

I'm looking for an algorithm which, when given a particular route on a map with attributes such as incline/distance/shape/etc, can find a route which is similar (in terms of the attributes) but starts ...
Chris Foster's user avatar
9 votes
1 answer
208 views

Is there a name for a situation when the place is clearly or unclearly named?

This is not specific to any system. Suppose there's a large red rock on a terrain which can be easily found and clearly seen and there's an artificial object such as a mall near that large red rock. ...
sharptooth's user avatar
9 votes
1 answer
463 views

Is "puntal" an accepted and defined geometric term?

There are definitions for the geometric qualities of polygons and lines: polygonal: Having many angles; hence characteristic of a polygon. Ref: http://en.wiktionary.org/wiki/polygonal ...
blah238's user avatar
  • 35.8k
8 votes
1 answer
143 views

What does "correctly noded" mean?

I've never seen this term, and I'm wondering what it means, with regard to ST_Polygonize NOTE: Input linework must be correctly noded for this function to work properly
Evan Carroll's user avatar
  • 7,081
8 votes
2 answers
2k views

How do MODIS products naming conventions work?

If I have the product MOD13Q1.A2014001, does it represent the previous 16 or the 16 days after January 1st? I.e., the product is made with 16 days, but how to determine if it was taken the previous ...
Esteven Muriillo's user avatar
8 votes
7 answers
2k views

Best definition for GIS today? [closed]

What is the best definition of Geographical Information Systems? Has the definition changed at all since I was taught it 10yrs back? The technology has changed a lot and it is more powerful than it ...
jakc's user avatar
  • 9,858
7 votes
1 answer
8k views

Difference between 'join' and 'merge'?

Suppose one wants to make polygons A and B, and their respective attributes to be one unique polygon C. What is this GIS operation called? Is there any difference in GIS terminology about "...
Andre Silva's user avatar
  • 10.3k
7 votes
3 answers
269 views

What's a term for Sea Level Distance which is usable by novice users?

I've been using the term Sea Level Distance to describe the total length of a line string where I ignore the elevation and just calculate the distance from point to point along the ellipsoid and sum ...
Sarge's user avatar
  • 457
6 votes
3 answers
464 views

Do I necessarily need coordinates for spatial prediction?

Commonly, it is stated that spatial prediction is the same as spatial interpolation, i.e. the estimation of values based on the observations' location: y ~ lon + lat Others state, that spatial ...
Funkwecker's user avatar
6 votes
1 answer
534 views

What does LW stand for in liblwgeom of PostGIS?

What does LW stand for in liblwgeom of PostGIS? I could not find any explanation anywhere, or in the source code (mirrored) at https://github.com/postgis/postgis/tree/svn-trunk/liblwgeom
Brian Burns's user avatar
6 votes
2 answers
1k views

What are the background/geography and foreground/data parts of a map called?

Consider a geographical map, e.g. a street map or satellite map, overlaid with some data, e.g. crime density or distance to closest voting booth. The former part is only used to orient the reader, so ...
Andreas's user avatar
  • 63
5 votes
2 answers
7k views

Which one is called inset map in this?

I am confused as to which one is technically the inset figure in the below map. I know an inset map is one which has more detail. But in this case which one is referred to as an inset map ...
GIS Data Butcher's user avatar
5 votes
1 answer
233 views

The term for determining the pixels of a raster image

I am looking for an english well-established term for determining: 1) invalid/nodata raster image pixels (№ 1 - black ones on the image below) and 2) valid/data raster image pixels (№ 2 - other ones ...
Comrade Che's user avatar
  • 7,206
5 votes
1 answer
1k views

Difference between control point, reference point, and tie point

I georeferenced a map using grid coordinate and road network shapefile (e.g. intersection vertex) as a control point. I didn't acquire a control point through the survey. I use "control point (...
astaga's user avatar
  • 123
5 votes
1 answer
78 views

Proper name for area defined by coordinate pair and radius

In defining geography objects within software, I have things such as a City Area, which is an area defined by the bounds of a city, or a County Area, defined by the county boundary. What is the ...
Brad's user avatar
  • 152
5 votes
1 answer
2k views

How many kinds of "address" are there? [closed]

I'm defining "address" as "a physical location, usually visibly numbered". Numbered was used in the definition to exclude purely geographical features not usually considered to have or need an ...
Witness Protection ID 44583292's user avatar
5 votes
1 answer
3k views

How is a geographic heat map different from a colored statistical thematic map?

From Wikipedia, A heat map is a graphical representation of data where the individual values contained in a matrix are represented as colors. Apparently, a geographic heat map is only one kind, ...
Martin F's user avatar
  • 8,946
4 votes
2 answers
312 views

"Official" definition to hyperspectral sensor

I was checking in the literature about a formal definition for hyperspectral sensors, and the most complete definition I found was from The Center of Space Research (@ University of Texas in Austin): ...
Gorgens's user avatar
  • 493
4 votes
1 answer
386 views

What are duck egg patterns in weighted moving average spatial interpolation method?

I'm dealing with spatial interpolation methods, in particular with the weighted moving average. I come across really oft with a term "duck egg patterns" which are caused by isolated data points. ...
user20159's user avatar
  • 915
4 votes
2 answers
6k views

What is the difference between Key-Point, Tie-Point in Photogrammetry?

I'm looking into the reports & the Mechanism of UAV Photogrammetry software like Pix4D and AgiSoft. These two words are mentioned in a lot of support documentation, but they are defined no-where. ...
Devdatta Tengshe's user avatar
4 votes
1 answer
2k views

Correct use of the terms geographic, path, and Euclidean distance

I often use the terms geographic and Euclidean distance interchangeably when referring to the length of the shortest straight-line distance between two points on a map. Is this correct? I use the ...
digitalmaps's user avatar
4 votes
1 answer
77 views

How to name this sort of edge?

I'm searching for a certain pathfinding algorithm which considers a certain sort of branch in the network. However, I find it difficult to define my search term as I do not know how this certain kind ...
i.i.k.'s user avatar
  • 1,575
4 votes
2 answers
576 views

Is there a source for common GIS terminology in French?

I am trying to find a a resource that provides English/French translations for GIS terminology. Obviously I could use Google or a French/English dictionary, but there are many cases where there are ...
dblanchett's user avatar
  • 1,356
4 votes
1 answer
211 views

What is the standard terminology for raster alignment?

I would like to identify two types of raster alignment (assuming SRS is the same), but I am unsure of the correct terminology for these (or whether there is even a 'standard')? First, there is 'pixel ...
James's user avatar
  • 2,268
3 votes
3 answers
1k views

Can ArcGIS Server be called ArcSDE? I'm confused about terminology

I'm confused about some ESRI terminology. If I have ArcGIS 10.1 Server installed and we use Enterprise geodatabases with versioning capabilities but we use direction connections does this have ...
ianbroad's user avatar
  • 9,141
3 votes
2 answers
152 views

Generic term for CRS axes?

We're making a light web front to a database, and I saw this in a test screenshot: Despite those coordinates being nowhere near North America, the "latitude/longitude" label for those ...
Mintx's user avatar
  • 5,396
3 votes
2 answers
81 views

What does n-D stand for in the following operator definitions?

PostGIS shows a listing of operators that make reference to n-D &&& — Returns TRUE if A's n-D bounding box intersects B's n-D bounding box. &&&(gidx,geometry) — Returns TRUE ...
Evan Carroll's user avatar
  • 7,081
3 votes
1 answer
215 views

Naming convention for ways of defining direction

The following two conventions for defining direction are very common, but what are they called? 0 at north, clockwise 0 at positive x-axis, counterclockwise Background: I'm writing a function that ...
blupp's user avatar
  • 141
3 votes
1 answer
53 views

Terminology for groupings/categories within ArcGIS Pro galleries?

In ArcGIS Pro 1.1.1, when I use the INSERT tab to insert a New Layout, I am offered a gallery of layout templates to choose from. I think the terminology that I have used so far matches that found in ...
PolyGeo's user avatar
  • 65.2k