01
Terrain profile
Height above sea level along the line, with length, lowest and highest point, total ascent and descent.
Elevation profile
Elevation profile and cable sag along any line
Draw a line on the map and see the terrain under it as an elevation profile. Give every point a pole height, set the cable sag and Geisro shows the ground clearance of the overhead line along the whole route, including every place where the cable would touch the ground.
5 m terrain model · pole heights · sag per 100 m span · ground clearance check
What it does
A terrain profile built for overhead lines
From a quick look at the terrain along a route to checking where a power line, a telecom cable or a fibre optic aerial cable needs taller poles.
02
Pole heights
Every point of the line is a pole with its own height above the terrain.
03
Cable sag
One sag per 100 m span; each span sags with the square of its length, as a parabola.
04
Ground clearance
Minimum clearance of the cable and every place where it would touch the ground, in red.
05
Edit in the chart
Drag a point to change its height, slide it along the route, double-click to add a pole.
06
Span table
Span length, total distance, sag, terrain and altitude of every pole in one table.
07
Saved with the line
Pole heights and sag are stored with the geometry and stay put when you edit the line.
08
Live readout
Hover the chart for distance from the start, terrain altitude and cable height above the ground.
Use cases
Plan overhead lines against the real terrain
A profile of the ground under a planned route answers the first question of every overhead line: where do the poles have to be taller, and which span is too long? Geisro gives you the answer on the map, without desktop GIS or a CAD tool.
- Distribution power lines (22 kV, 35 kV) and low voltage lines
- High voltage transmission line route studies
- Telecom and fibre optic aerial cables on poles
- Ropeways, zip lines and cable crossings of valleys
- Terrain profile of a road, trail, pipeline or canal route
How it works
How to make an elevation profile and check cable clearance
- Draw the lineDraw the planned cable or power line route, one point per pole.
- Open the elevation profileSelect the line and choose Elevation profile from its menu.
- Set pole heightsType the height above terrain of every point, or drag the points in the chart.
- Set the cable sagEnter the sag per 100 m span - longer spans sag more, shorter spans less.
- Check and saveRead the minimum ground clearance, fix the red spans, and save with the line.
The sag of a span grows with the square of its length: at 2 m per 100 m, a 150 m span sags 4.5 m and a 300 m span 18 m. That is why a single long span over a valley is usually the first place a cable gets too close to the ground.
Terrain data
Official terrain data, kept on our own servers
Heights come from official open digital terrain models, not from the map tiles. Today Geisro covers the Czech Republic with the 5 m digital terrain model DMR 4G (bare ground from airborne laser scanning, © ČÚZK), and more countries are on the way. A line that leaves the covered area shows a hatched "no data" gap, and every such country is recorded, so we know where to add terrain data next.
FAQ
Frequently asked questions
What is an elevation profile?
A cross-section of the terrain along a line: the height above sea level plotted against the distance from the start. Geisro draws it for any line on the map and adds the length, lowest and highest point, total ascent and descent.
How is the cable sag calculated?
You enter the sag at the middle of a 100 m span. Each span then sags as a parabola by that value times the square of its length divided by 100 m, so a 200 m span sags four times as much. It models one cable with one tension along the whole line.
Can I check the ground clearance of an overhead line?
Yes. Geisro shows the minimum clearance between the cable and the terrain and where it occurs, and highlights in red every place where the cable would go below the ground.
Which terrain data does Geisro use?
Its own copy of official open terrain data. Today that is the Czech Republic with the 5 m model DMR 4G from ČÚZK; more countries are being added.
Is it a replacement for a power line design?
No. It is an approximate calculation for planning and checking routes: one state, a parabola, without temperature, ice or wind load. A real overhead line design must follow the applicable standards.
Which plans include it?
The elevation profile, pole heights and cable sag are included in the Pro, Ultra and Team plans, with no limit on the number of profiles - see pricing.
Ready when you are
Draw a line and see the terrain under it
N 50.7360 E 15.7397 · GEISRO ELEVATION PROFILE