Version
1.1.0.12 (preview)
Language
English
You are reading the Icon Map Slicer documentation for version 1.1.0.12, which has not been released yet. Go to the latest version (1.1.0.11).

Shapes at their heights (WKT and GeoJSON with Z)

New in 1.1.0.12

With Use Z heights on, the Shapes (from data) layer draws each shape in 3D space, at the height held in each of its coordinates. An aircraft's track climbs out of the airport, a pipeline stays level as it crosses a valley, and an airspace sector floats at its floor.

Aircraft tracks climbing away from Heathrow in 3D on a tilted map, with an aircraft model at the head of each track
Departures drawn at their heights, with the aircraft as 3D models

What you need

The same fields as Shapes from data: an ID and the shape in Image / WKT / GeoJSON. The difference is in the text: each coordinate carries a third number, its height.

ID Image / WKT / GeoJSON
BA117 LINESTRING Z (-0.4543 51.4700 25, -0.5200 51.4780 600, -0.6400 51.4950 1500)
Pipeline 7 LINESTRING (-3.21 55.86 240, -3.18 55.86 240, -3.15 55.87 240)
Sector 3 POLYGON Z ((-1.2 51.6 2000, -0.9 51.6 2000, -0.9 51.4 2000, -1.2 51.4 2000, -1.2 51.6 2000))
Waypoint {"type":"Point","coordinates":[-0.19,51.15,3000]}

Turn it on

  1. Add the Shapes (from data) layer as usual. See Add the layer.
  2. In Format pane > Data Layers > Shapes (from data) - Configuration, switch on Use Z heights.
  3. Set Heights are above to Sea level or Ground, and Height units to Meters or Feet.
  4. Tilt the map to see the heights. See View, zoom and projection.

The same three settings are in the Layer Manager: select the Shapes (from data) row. See Edit, reorder and remove layers.

Use Z heights is off by default, so a report whose text happens to carry heights keeps drawing its shapes flat until you turn it on. Rows without heights are drawn flat as before, so one layer can hold both.

Heights in WKT and GeoJSON

WKT

The height is the third number of each coordinate. Any of these forms works:

Form Example
A Z tag LINESTRING Z (-0.45 51.47 25, -0.52 51.48 600)
A ZM tag LINESTRING ZM (-0.45 51.47 25 0, -0.52 51.48 600 60). The fourth number (M, a measure) is read and ignored.
Three numbers with no tag LINESTRING (-0.45 51.47 25, -0.52 51.48 600)
The tag joined to the type LINESTRINGZ (...)

POINT, MULTIPOINT, LINESTRING, MULTILINESTRING, POLYGON, MULTIPOLYGON and GEOMETRYCOLLECTION all take heights. While Use Z heights is on, MULTILINESTRING Z and MULTIPOLYGON Z text, which the flat layer cannot read, is read too. A geometry tagged M only has no heights.

GeoJSON

GeoJSON has heights built in. The GeoJSON standard (RFC 7946) allows a third number in each position, the altitude: [longitude, latitude, altitude]. Geometries and Features both work, as for the flat layer.

{"type":"LineString","coordinates":[[-0.4543,51.47,25],[-0.52,51.478,600],[-0.64,51.495,1500]]}

Units and coordinate systems

Heights are in Height units: Meters or Feet. Flight data often gives altitudes in feet. With an EPSG code set, longitude and latitude are converted and the heights are kept as they are.

What a height is measured from

Heights are above decides where a height of 0 is:

Heights are above What it means Use it for
Sea level (the default) Each height is an altitude above sea level. With 3D terrain exaggerated, the heights are multiplied by the same exaggeration, so the shapes stay in step with the hills. Aircraft tracks, airspace, pipelines and power lines whose heights were surveyed as altitudes
Ground Each height is above the 3D terrain under that point. With no 3D terrain, it is the same as Sea level. Cables and drone routes given as a height above the ground
A line at 300 meters above sea level held level across a valley, and a line 50 meters above the ground that follows the hills
Sea level holds a shape at its altitude; Ground follows the terrain
A pipeline on 3D terrain held level across a valley, beside the same route draped on the ground
The same pipeline with Use Z heights on, and draped on the ground

When 3D terrain loads after the shapes, shapes measured from Ground move up to the terrain as its tiles arrive. See Terrain, hillshade, sky and lighting.

Missing heights

Not every coordinate needs a height. In WKT, a coordinate with two numbers has no height. In GeoJSON, a position with two numbers has none.

  • In a line, a missing height between two coordinates that have one is filled in, in proportion to the distance along the line. A track with a height at every tenth point is still drawn as a smooth climb.
  • At either end of a line, a missing height leaves the whole line flat on the map, because there is nothing to fill it from on that side.
  • In a point or a polygon, every coordinate needs a height. If one is missing, the shape is drawn flat.
  • In a collection, the members that have their heights are drawn at them and the rest are drawn flat.
A line with heights at its first, third and last points: the missing heights between are filled along the line; a line with no height at its end is drawn flat
Missing heights in the middle are filled; a missing end leaves the line flat

How the shapes are drawn

Holding stacks drawn as rising rings and airspace sectors as floating slabs over a tilted map
Airspace sectors and holding stacks at their heights

A row drawn at its heights uses the layer's own settings, including their conditional formatting:

Part Settings that apply
Lines and polygon outlines Outline Color, Outline Transparency, Outline Width, Outline Blur, and Color Type with Gradient Color 1 and Gradient Color 2.
Polygon fills Fill Color and Fill Transparency. A polygon whose corners are at different heights is drawn sloping.
Points A circle of Circle Size, in the fill color with the outline color around it.

While Use Z heights is on, some options are not offered or do not apply to the rows drawn at their heights:

  • Linestring Shape does not offer Routes, and Fill Style offers Solid only.
  • A line drawn at its heights runs straight between its points: Smoothed and Bezier apply to flat lines.
  • Line symbols, the images at the start and end of a line, polygon extrusion and data labels are drawn for flat shapes only.
  • Points drawn at their heights are circles, whatever Show Points As is set to.
  • Simplify When Zoomed Out does not apply: heights are drawn as given.

Shapes are drawn on the flat map and on the globe. On the globe, shapes on the far side are hidden.

Selection, tooltips and zoom

  • Selection. Click a line, polygon or point where it is drawn, in the air, to select its row and filter the rest of the report page. The lasso and circle select shapes where they are drawn on screen. Other shapes fade to Unselected Items Transparency in Format pane > Selection > Formatting. See How Icon Map Slicer filters.
  • Tooltips. Pointing at a shape shows the fields in Tooltips.
  • Zoom. Auto zoom, and zooming to the selection, frame the shapes at their heights, so a track that climbs to cruise altitude stays on screen.
  • Drawing order. The shapes keep the layer's Z Index place, and move with the Shapes (from data) row in the Layer Manager.

Settings

These are in Format pane > Data Layers > Shapes (from data) - Configuration. They apply to the whole layer and do not take conditional formatting.

Setting What it does Default
Use Z heights Draws shapes whose WKT or GeoJSON has a height at each coordinate at those heights. Shapes without heights are drawn as before. Off
Heights are above Sea level: each height is above sea level. Ground: each height is above the 3D terrain under it. Shown when Use Z heights is on. Sea level
Height units Meters or Feet. Shown when Use Z heights is on. Meters

Every other setting is described in Shapes from data (WKT and GeoJSON).

Tips

  • A shape is flat. Check the ends of a line: both need a height. Check that Use Z heights is on.
  • The shapes are far too high or too low. Check Height units. Altitudes in feet read as meters draw over three times too high.
  • A line dips into the hills. With Sea level, a line lower than the terrain goes under it. Check the heights, or use Ground for heights given above the ground.
  • To draw an aircraft at the head of its track, put the aircraft on a separate row in the 3D models layer, with Sit on terrain off and the same height.
  • Shapes (from files) and catalog layers are drawn on the ground.