Routing rules and off-road anchors

Each click you place becomes one segment of the route line. What shape that segment takes depends on the routing mode you are in and on how close the click landed to a road or trail. The rules below tell you which shape you get, so a straight line across open country reads as the result of where you clicked rather than a fault in the route.

The order of attempts#

In Auto, INVIA works through three sources for each new click, in this order.

1. The road network.
2. The trail network.
3. A straight line.

The first attempt that finds something within tolerance is the one you get, so Auto gives you road routing where a road is close and a straight line where nothing is.

Pick the mode by what you are drawing, because Road and Trail hold every click to one network while OFF-Track skips routing so the line goes exactly where you click.

Switching modes#

Switching modes changes only the segments you draw next, so you can start in Road, switch to OFF-Track for a stretch of open ground, and switch back. Nothing already drawn moves. The route line, its points and its distance stay as they were, and to move a section you have already drawn you use Detour rather than a mode switch.

An orange anchor already on the route keeps its color and its straight line when you switch to Road, because the new mode applies only to the points you add next. The anchor survives later edits as well. Once a stretch has been drawn off-road it is locked, so dragging a neighboring point re-routes the road parts around it without straightening the anchor out or putting it back on a road.

Snap tolerance follows zoom#

How close a click has to be to count as on a road depends on how far you are zoomed in. At a wide zoom your click can only be so precise, so INVIA accepts a click much further from the road than it does at street level.

The same click can snap at one zoom and be declared off-road at another. Zoom in before you click when the exact road matters, so the click falls inside the tighter street-level tolerance and picks the road you meant. The tolerance belongs to Auto, because Auto is the mode that chooses between a road, a trail and a straight line, so Road, Trail and OFF-Track measure no distance at all.

A far click in Road or Trail#

In Road and in Trail every click is accepted, because neither mode measures how far your click landed from a road or a trail. A click out in open ground is never refused and never becomes an orange anchor.

• In Road, the road router joins the click to the rest of the route by road, however long a way round that takes.
• In Trail, the trail router works from the nearest trail it can find.
• Straight lines and orange anchors come from Auto and from OFF-Track, and from nowhere else.

The only failure Trail reports is a total one, because a stretch that cannot be routed on trails at all is redrawn as a road route, and INVIA tells you it did.

The off-road chain#

A click that finds nothing within tolerance on either network starts an off-road chain, because INVIA draws the line where you put it rather than pulling your point across to the nearest road. An off-road chain therefore only ever starts in Auto, because OFF-Track draws every segment straight and Road and Trail never declare a click off-road.

What you see:

• The segment is drawn as a straight line, so the route has no gap in it.
• The point becomes an orange anchor. An orange anchor is a point that is not on a road, with the line drawn exactly through it.
• The route is still one route, and the points before the anchor do not move.

The chain continues for as long as your clicks keep landing away from a road, with each new click adding another straight line. The chain ends when a click lands within about 10 meters of a road. Road routing resumes from that click, which is how you get routed segments back without changing any setting.

Dragging an anchor#

Orange anchors are the one part of the line you can drag, so an off-road leg can be corrected in place instead of deleted and drawn again.

1. Zoom in to zoom 11 or closer.
2. Drag the anchor where you want it.

The two straight segments on either side of the anchor are redrawn as you drag. Nothing has to be fetched before the redraw, so the new shape appears without a pause.

Anchors below zoom 11#

Anchors fade as you zoom out, and below zoom 11 the anchor markers are not drawn. A long route seen from far away stays a clean line rather than a row of dots.

• The anchors are still on the route. Only the markers are hidden.
• The route line, its distance and its shape do not change.
• Zoom back in to zoom 11 or closer to see the anchors and drag them again.

When the trail router is unavailable#

If the trail network cannot be reached, INVIA routes that segment on roads instead and tells you it did, so you are left with a complete line rather than a gap.

The notice is a dark bar centered near the top of the screen, just under the nav bar. It reads:

Trail routing (BRouter) is unavailable - showing road route instead.

It fades out on its own after about three seconds, which means there is nothing to dismiss and nothing to click, and the segment it tells you about is already drawn.

• The segment is drawn. It follows roads instead of trails.
• The rest of the route is untouched, so the segments you drew earlier keep the shape they had.
• Nothing is required of you. The route is complete and you can keep building.
• To draw that segment off the road network instead, switch to OFF-Track and place the points again, which puts every click on a straight line of your own.

Road-only options#

Three options apply in Road mode only, and each one narrows the roads INVIA is allowed to use.

• Avoid Highways
• Avoid Tolls
• Avoid Unpaved

Turning one on or off re-routes the whole route, because the rule has to hold for every segment and not only the ones you draw next. Your route points stay where you placed them. Only the line between them is redrawn. In Auto, Trail and OFF-Track the three options do not apply.