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GIS Professional Forest GIS, GNSS & LiDAR Analytics: practice questions

GIS Professional (GISP) · International · GIS Certification Institute

Original practice questions written to the published syllabus · not past papers
10worked here, free
19written to this exam in this subject
6syllabus units

What this subject covers

Spatial data and analysis for forest management: GIS data models, spatial analysis, GNSS, airborne and terrestrial LiDAR, and the digital tools of precision forestry. General remote sensing and GIS for land and water is in the Agricultural Engineering track (remote-sensing-gis).

In the exams: ICAR AICE-JRF 59 Unit 4 (GIS and remote sensing concept and scope); GISP and ASPRS certifications; growing share of SAF and FPBC professional practice

Where the 19 questions fall

How our questions for GIS Professional spread across the units of Forest GIS, GNSS & LiDAR Analytics. Difficulty: 5 easy, 12 medium, 2 hard.

GIS concepts: vector and raster data, projections, datums4
Map production and cartographic standards4
Spatial analysis: overlay, buffer, terrain analysis3
Forest stand and compartment databases3
Spatial decision support and multi-criteria analysis3
Open data and cloud platforms for forest monitoring2

10 practice questions, worked

Choose an answer, then open the working. Each explanation says why the right answer is right and why the others are not.

1 · GIS concepts: vector and raster data, projections, datums · medium

A plot centre lies at longitude 37.5° E. In which UTM zone is it?

  1. 37
  2. 36
  3. 38
  4. 7
Answer and working

A. 37

Zone = floor((longitude + 180) ÷ 6) + 1 = floor(217.5 ÷ 6) + 1 = 36 + 1 = 37. Using the floor without adding 1 gives 36.

Further reading: Longley P; Bolstad P; Wulder M; Maltamo M

2 · GIS concepts: vector and raster data, projections, datums · medium

Why is a false easting of 500,000 m assigned to each UTM zone's central meridian?

  1. To keep all eastings in the zone positive
  2. To make the zone conformal at its edges
  3. To convert the datum from local to WGS 84
  4. To equalise the scale factor across the zone
Answer and working

A. To keep all eastings in the zone positive

Points west of the central meridian would otherwise have negative eastings. The false easting does not change scale or datum; the scale factor 0.9996 on the central meridian handles distortion.

Further reading: Longley P; Bolstad P; Wulder M; Maltamo M

3 · Spatial analysis: overlay, buffer, terrain analysis · easy

Tiny polygons that appear along shared boundaries after overlaying two independently digitised layers are called:

  1. Sliver polygons
  2. Dangling nodes
  3. Pseudo nodes
  4. Donut polygons
Answer and working

A. Sliver polygons

Slivers form where two versions of the same boundary do not coincide. Dangling nodes are unconnected line ends; pseudo nodes join only two lines; a donut polygon has a hole.

Further reading: Longley P; Bolstad P; Wulder M; Maltamo M

4 · Spatial analysis: overlay, buffer, terrain analysis · hard

Before deriving a stream network from a DEM, small depressions are filled. Why?

  1. Spurious sinks would stop flow and break the network
  2. Filling smooths the slopes so that aspect can then be calculated
  3. Depressions make the DEM file too large to process
  4. Filling converts the DSM into a bare-earth DTM
Answer and working

A. Spurious sinks would stop flow and break the network

Artificial pits trap flow, so accumulation stops and streams are fragmented. Filling does not remove vegetation or change a DSM into a DTM.

Further reading: Longley P; Bolstad P; Wulder M; Maltamo M

5 · Spatial decision support and multi-criteria analysis · medium

A cell scores 0.8 for slope, 0.4 for access and 0.6 for soil (standardised 0–1), with weights 0.5, 0.3 and 0.2. Its WLC suitability is:

  1. 0.60
  2. 0.64
  3. 1.80
  4. 0.40
Answer and working

B. 0.64

0.5 × 0.8 + 0.3 × 0.4 + 0.2 × 0.6 = 0.40 + 0.12 + 0.12 = 0.64. 0.60 is the unweighted mean; 1.80 is the unweighted sum.

Further reading: Longley P; Bolstad P; Wulder M; Maltamo M

6 · Spatial decision support and multi-criteria analysis · easy

Before combining distance to road (metres) and soil fertility (index) in MCA, factors are:

  1. Multiplied together without any rescaling
  2. Converted to Boolean yes/no layers in all cases
  3. Added in their original units
  4. Standardised to a common scale such as 0–1
Answer and working

D. Standardised to a common scale such as 0–1

Factors in different units must be standardised, by linear rescaling or fuzzy functions, before weighting.

Further reading: Longley P; Bolstad P; Wulder M; Maltamo M

7 · Open data and cloud platforms for forest monitoring · medium

An analyst wants to read only one small window of a very large image stored online without downloading it all. Which format feature makes this possible?

  1. A compressed archive of the whole image
  2. Conversion of the image to a vector layer
  3. A printed map of the image at small scale
  4. A cloud-optimised raster with internal tiles
Answer and working

D. A cloud-optimised raster with internal tiles

Cloud-optimised formats are internally tiled with overviews so that clients request only the needed byte ranges.

Further reading: Longley P; Bolstad P; Wulder M; Maltamo M

8 · Map production and cartographic standards · easy

Which colour scheme suits a map of change in canopy height, with losses and gains around zero?

  1. Sequential
  2. Qualitative
  3. Single-hue binary
  4. Diverging
Answer and working

D. Diverging

Diverging schemes use two hues meeting at a neutral midpoint. Sequential schemes suit values from low to high; qualitative suit categories.

Further reading: Longley P; Bolstad P; Wulder M; Maltamo M

9 · Map production and cartographic standards · medium

A choropleth map of districts shows total timber volume, so the largest districts look darkest. The better choice is to map:

  1. Total volume with more classes
  2. Total volume in a qualitative scheme
  3. District area in a sequential scheme
  4. Volume per hectare
Answer and working

D. Volume per hectare

Choropleths should map rates or densities; totals are driven by area. Adding classes or changing scheme does not fix the problem.

Further reading: Longley P; Bolstad P; Wulder M; Maltamo M

10 · Map production and cartographic standards · medium

200 stands are classified into 5 classes of volume by the quantile method. Each class contains:

  1. 40 stands
  2. 5 stands
  3. 20 stands
  4. Classes of equal width, so it varies
Answer and working

A. 40 stands

Quantile classes have equal numbers of features: 200 ÷ 5 = 40. Equal-width classes describe the equal-interval method.

Further reading: Longley P; Bolstad P; Wulder M; Maltamo M

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Read the subject

Forest GIS, GNSS & LiDAR AnalyticsThe full study manual, free GIS ProfessionalFormat, sections and how it has changed

Forest GIS, GNSS & LiDAR Analytics for other exams

ICAR AICE-JRF/SRF · IndiaSAF Certified Forester · USA

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