Top 29 GIS Interview Questions that can help you land your dream job!!!

Have you ever wondered what could be the questions that be asked in your interview? Ever wonder how you would answer those questions? Then, here are some general questions/answers that are frequently asked in the interviews.

Well, good luck for those who are appearing for an interview.

1.    
What is GIS?

GIS stands for “Geographic Information System”. It is a set of computer tools that allows to work with data that are tied to a particular location on the earth. GIS is more than just a mapping system because it does some sophisticated spatial analysis, network analysis, geocoding and geo-referencing, and many more.

A GIS is a database system that uses both spatial and attribute data to answer questions about where things are and how they are related. It has many functions, including creating data, making maps, and analyzing relationships.

2.    What can GIS do?

GIS works with different applications: land use planning, environmental management, sociological analysis, business marketing, weather prediction, city planning, waste-water panning, urban planning, navigation tools, and many more. 

3. What are Map data types?

This is little bit tricky because most people confuse themselves with map data types and data formats. There are two types of map data: Discrete and Continuous.

Discrete: objects in real world with specific locations or boundaries, such as cities, roads, or soil units

Continuous: quantity that is measured and recorded everywhere over a surface, such as temp or elevation

4. What are Data formats?

There are two data formats that GIS is handy with: Vector and Raster data formats. Both data systems store spatial and attribute data, but in different ways. Both are georeferenced, meaning that the information is tied to a specific location on the earth’s surface using x-y coordinates defined in a standard way: a coordinate system.

Vector model:
stores discrete data—eg, points (no dimension), lines (1D), and polygons (2D).

• Benefits of vector models:
  • Can store individual feature classes, such as
    roads and parcels, with high degree of precision
  • Linked attribute table provides great
    flexibility in the number and type of attributes that can be stored about each
    feature.
  • Ideally suited for mapmaking because of high
    precision and detail—it is a compact way of storing data
  • Ideally situated to certain types of analysis
    problems, such as determining perimeters and areas, detecting whether features
    overlap, and modeling flow through networks.
• Drawbacks
  • Poorly adapted to storing continuous surfaces,
    such as elevation or precipitation.
  • Contours lines can be used to represent
    surfaces, but calculating derived information from contours such as slope, flow
    direction, and aspects, is difficult.
  • Some analysis is more time consuming

Raster Model:
stores continuous data—set of spatial data represented as series of small
squares called cells or pixels. Each pixel contains a numeric code indicating a
single attribute, and the raster is stored as an array of numbers. Eg, DEM.

• Benefits of Rater model:
  • Ideally suited to store continuous information because each cell can have a value completely different from its neighbors.
  • Simple and rapid analyses.
  • Extensive set of analyses tools for raster available.
• Drawbacks of raster:
  • Suffer from trade-offs between precision and storage space to a greater extent than vectors do.
  • Can store only one numeric attribute per raster, whereas vector can store hundreds of attribute values for each spatial feature and can handle text data more efficiently.

5.     What are feature classes?

In GIS, like features are grouped into data sets called feature classes. A feature class can contain only one kind of geometry—point, line, or polygon. Feature classes can be stored in several different formats. Some formats contain only one feature class, whereas some store multiple feature classes and are called feature datasets.

Read: What are the similarities and differences between Shapefile and Feature Class? and What are Feature Classes?

6.    What are attributes?

Objects in feature class have information stored about them, such as their name and populations. This information is called attributes and is stored in table.

7.     What is map scale?

Map scale is a measure of the size at which features in a map are represented. The scale is represented as a fraction, or ration, of the size of objects in the page to the size of the objects on the ground. Large-scale maps (with smaller denominator) show a relatively small area, such as quadrangle, whereas small-scale maps (with large denominator) show a relatively larger areas, such as states or countries.

8.     What is Resolution?

Resolution refers to the sampling interval at which data are
acquired. Resolution may be spatial, thematic, or temporal.

• Spatial resolution indicates at what distance interval measurements are taken or recorded.
• Temporal resolution indicates how frequently measurements are taken. Eg, census, temperature, precipitation etc.

9.     What is precision?

Precision refers to either number of significant digits used to record a measurement or the statistical variation of a repeated single measurement.

10.     What is metadata?

Metadata is a data of the data which stores information about the dataset, such as where it came from, how it was developed, who assembled it, how precise it is, and whether it can be given to another person.

11.     What are shapefiles?

Shapefiles are spaghetti data models containing a features
class composed of points, lines, or polygons, but never a mixture. The
attributes are stored in dBase file. Shapefiles can store multipart features,
in which a single feature includes multiple objects.

• .shp file stores coordinate data
• .dbf file stores attribute data
• .shx file stores a spatial index that speeds drawing and analysis
• .prj file stores projection information
• .avl file is a stored legend
• .xml file contains metadata

Read: What are the similarities and differences between Shapefile and Feature Class? and What are Shapefiles?

12.     What are geodatabases?

A geodatabase can contain many different objects, including feature classes, networks, tables, raster, and topology. There are 3 types of geodatabases:

1. Personal geodatabases: designed by use by individuals or small workgroups and are stored in a single Microsoft Access file. –limited to 2GB.
2. File geodatabases: stored in system folder, and each file can be up to 1TB. –can be accessed by multiple operating systems, including Linux or Unix.
3. Enterprise (SDE) geodatabase: stores GIS data within a commercial relational database management systems (RDBMS), such as Oracle or SQL Server. —designed to meet security and management needs for large data sets accessed by multiple users.

13.     What is geographic coordinate system (GCS)?

It is a measurement of angles from the center of the earth and has units of degrees. Longitudes—measure horizontal angles east or west of the Prime Meridian (-180 to +180), and Latitudes are vertical angles above or below the equator (0 to -90, 0 to +90).

Also read: What are the differences between Geographic and Projected Coordinate Systems?

14.     What is Map Projection?

A GCS is a three-dimensional coordinate system, but maps need to be flat. The conversion of 3D map into 2D map is called Map Projection. Projection is mainly done to avoid distortions: Area, Distance, Shape, and Direction. (Read: What is a Map Projection? What are different Map Projections used in GIS?)

Based on shape of the surface onto which GCS loactions are projected, the projections are grouped into 3 major classes:

1. Cylindrical Projection: uses a cylindrical surface that lies tangent to (touches) the earth at the equator along a great circle. Cylindrical Projections are of 3 types:
   1. Equilateral: surface tangent to the earth at equator
   2. Transverse: rotate the cylinder sideways making it tangent along a line of longitude
   3. Oblique: places tangent at an angle
2. Conic Projection: uses cone on the sphere
   1. Tangent: cone is tangent to the globe along the line of latitude
   2. Secant: cone is places through the sphere touching two places
3. Azimuthal Projection: a plane is placed tangent or secant to the sphere. This projections are used for displaying the earth’s poles, and for that reason they are sometime called polar projections. Other names for this method are stereographic and orthographic projection.