Tree and building heights from LiDAR, anywhere in New Zealand

Who uses this

• Arborists. Screen tree heights across a property or a street.
• Planners and neighbours. Get approximate building and hedge heights for a shading or view question.

When to use it

• Checking shelterbelt or tree heights for shading, view or line-of-sight questions.
• Getting approximate roof heights across a neighbourhood.
• Seeing what stands on a block before visiting.

Which tool for your job

Object Heights is one step in a bigger question. These are the jobs it helps with, and the tools that go with it.

How to use it

1. Select a property, draw an area or upload a boundary.
2. Run. Heights are drawn from tan (nothing above ground) to deep blue (tallest).
3. Read the coverage, the minimum, mean and maximum in the panel. For ground elevation use Terrain Stats instead.

Step by step: Mt Iron, Wānaka

We measure trees and houses around the foot of Mt Iron from the LiDAR surface model.

What it showed

• Buildings and trees are not told apart; compare with the aerial photo.
• Heights are as of the LiDAR flight. Trees planted or felled since will not show.

Screenshots from NZ Elevation Tools. Aerial imagery from LINZ Basemaps. Sourced from the LINZ Data Service and licensed by Environment Southland, Otago Regional Council and Queenstown-Lakes District Council for re-use under the Creative Commons Attribution 4.0 International licence.

How it works

LiDAR surveys publish two models: the bare earth with everything stripped off, and the surface, which is the top of whatever the laser hit first. Subtracting one from the other, cell by cell, leaves the height of trees, buildings and other objects.

Cells with no surface data, an obvious no-data value, or a surface below the ground are left blank. The colour scale is stretched between the 2nd and 98th percentile so a single tall tree does not wash out the rest.

Reading the results

Values are metres above ground, not elevation. A 2 m reading on a paddock is a fence line or a hedge; a 25 m reading is a mature tree or a two-storey building plus roof.

Buildings and vegetation are not told apart. Use the aerial basemap to see which is which.

Limits and warnings

• Only where LiDAR has been flown, and only as things were on the capture date.
• Over cliffs, rock and ice the two models diverge for reasons unrelated to objects. The tool warns when most of the area is steeper than 30 degrees, and readings there should be ignored.
• The surface and bare-earth models can come from different dates in the same area.

Data and attribution

Results come from the LINZ national 1 m LiDAR bare-earth elevation model, read in your browser, with the national 8 m model filling any gaps. Tools that use the surface model (Sunlight, Viewshed, Object Heights) read the matching LiDAR surface tiles.

Elevation and cadastral data is sourced from the LINZ Data Service and licensed for re-use under the Creative Commons Attribution 4.0 International licence. Copyright in each LiDAR survey belongs to the body that commissioned it — a regional or district council, Waka Kotahi, NIWA and around thirty others — rather than to LINZ, which hosts and processes the national dataset. Every file exported from this site names the licensors whose surveys cover the area, and anything you publish from those files carries the same attribution requirement. See https://www.linz.govt.nz/products-services/data/licensing-and-using-data/attributing-elevation-or-aerial-imagery-data

Questions

Related

Neighbouring tools

• Terrain Stats — Summarises the minimum, maximum, mean and range of ground elevation across an area, with a chart of how much land sits at each height.
• Sunlight — Models hours of direct sun across a site on any day of the year, with shadows from terrain up to 3 km away and, where LiDAR has been flown, from trees and buildings.
• Viewshed — Shows which ground within 1 to 10 km can be seen from a point, for a chosen eye height, with earth curvature and refraction allowed for and, optionally, trees and buildings blocking the view.