Is it possible to display "off-course distance"?

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Is it possible to display "off-course distance"?

Postby tedblank » 2017-04-25 19:12

In many handheld GPS units, for example Garmin GPSMAP64, you can define a "track" which is just a straight line between two points, like a boat might follow on a long trip.

Then the GPS unit can be told to display your distance off this course, always perpendicular distance of course. Garmin calls this "off-course distance", it might also be called "off-track distance".

Can Map Plus be set up to do this?

Thanks!
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Re: Is it possible to display "off-course distance"?

Postby Zax » 2017-04-26 0:22

tedblank wrote:In many handheld GPS units, for example Garmin GPSMAP64, you can define a "track" which is just a straight line between two points, like a boat might follow on a long trip.

Then the GPS unit can be told to display your distance off this course, always perpendicular distance of course. Garmin calls this "off-course distance", it might also be called "off-track distance".

Can Map Plus be set up to do this?

Thanks!


Yes, you can do that.

1) First create a line or custom route as you wish.
1.a) For how to create a line, please refer: http://www.duweis.com/support/viewdoc.h ... =090_shape
1.b) For how to create a custom route, please refer to: http://www.duweis.com/support/viewdoc.h ... =100_route

2) Select the line or route, and choose "follow", please refer to:
http://www.duweis.com/support/viewdoc.h ... 030_follow
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Re: Is it possible to display "off-course distance"?

Postby tedblank » 2017-04-26 3:52

This sounds very good! However, in our case the distances might be large.

For example, let's say I define a track that goes east to west in a straight line for 200 km.

Now I approach the track from the north in a car.

If I am 100 km from the track, will the offset say 100 km? (Yes, km, not meters).

When I reach the track, will the offset say 0?

If I drive past the track, will the offset be negative?

Thanks,
Ted
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Re: Is it possible to display "off-course distance"?

Postby Zax » 2017-04-26 5:48

tedblank wrote:If I am 100 km from the track, will the offset say 100 km? (Yes, km, not meters).

When I reach the track, will the offset say 0?

If I drive past the track, will the offset be negative?

Thanks,
Ted


1) Any line/route/track, with coordinate points more than 3, could be "followed".
While in the following status, when you select a line/route/track on the map, the offset distance, which indicates the perpendicular distance from your current position to the nearest point on the line, would be displayed in the info panel of it.

2) BUT, currently, the following function only works if you are closed enough to the target line/route/track, which means if you are too far away from the line, the app would thought you do not want to follow any more, and quit the following immediately.
For a polyline, the "closed enough" distance means within about 900 meters.
For a searched out route, the "closed enough" distance means within about 900 meters.
For a custom route with waypoints, the "closed enough" distance means within about 3000 meters.
In current version, the app could not follow a path if offset distance is larger than the listed above.

3) For your questions:
-- If I am 100 km from the track, will the offset say 100 km? (Yes, km, not meters).
no, it would quit following immediate, you can only follow a path which is 1000 meters far away from your current position.

-- When I reach the track, will the offset say 0?
yes, will display as "no offset"

-- If I drive past the track, will the offset be negative?
no, never be negative, the distance is the perpendicular distance to the nearest point of the path, no considering about the side.

4) More:
> Have you tried the Search Route function in the app, which provided a more detailed direction route for driving, and voice guidance is supported?

>You can edit a polyline, or create a custom route, with more coordinates(points) so that the path could be more specified and detailed, and you can follow such path without being too far away from it.

>If you want to display a large distance from current position to a place, please try the Guide Mark function. Select a destination place, going to its detail information, turn on the Guide Mark, then back to map, and move the map so that the place is off-screen, now you'll see a indicator on the screen edge shows how far away you are from it.
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Re: Is it possible to display "off-course distance"?

Postby tedblank » 2017-04-26 14:12

Thank you. I have been experimenting with the Guide Mark function. The guide mark (small blue arrow) always appears. However, the distance indicator only appears if you are within 100 km of the destination. Is this how the function currently works?

The event I'm working on is a scientific expedition to measure an eclipse. It will happen on June 3. We will have multiple telescopes along a N-S road. We want to make sure that each telescope is the correct distance from our base camp. Some of the stations might be 150 km or 200 km from the base location. Can this 100 km limit be increased?

Will the app (and guide mark feature) work in South America or Africa? This is where the telescopes will be set up (Argentina and South Africa).

What level of purchase is required to keep the 'guide mark' feature working?

Thanks!
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Re: Is it possible to display "off-course distance"?

Postby Zax » 2017-04-26 15:17

tedblank wrote:Thank you. I have been ....


---- The guide mark (small blue arrow) always appears
In current design, the guide mark for current position is always on and could not be turned off, except you stop the locating.

---- the distance indicator only appears if you are within 100 km of the destination
It is the design, we may adjust it later. What's more, please notice that the distance is from the screen center to the place (out of screen).

---- We want to make sure that each telescope is the correct distance from our base camp
There are many other ways to help you get a accurate distance from one point to another,
1) Using the "Directional Move" to move a point from one place(e.g. camp) with a fixed distance and direction. For example, toggle to editing mode, turn on the Magnetic Snap, Long press to drop a pin, drag it to snap to your camp point, then select it and choose "move" > "Directional Move", input the distance and the angle, and save the moved pin.
2) Using the measuring functions to do any measurement of distance and area.
3) Draw lines on the map with labels enabled and set it label to be the distances in KM, you need to use a expression like this: " round([:meters]/1000) + 'km' ".
What's more, with feature class and relationship building function, you can link the camp and the line and the telescope, so that while dragging the camp or telescope, the line would be updated automatically. (Sorry but the detail could not be explain here, since it is little bit complicated)
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----Can this 100 km limit be increased?
We may do that in later versions, but not recently.

----Will the app (and guide mark feature) work in South America or Africa?
Sure, there is no limitation of using area, except the south and north poles (latitude larger than 84, which could not be displayed in Web Mercator projected maps).

---What level of purchase is required to keep the 'guide mark' feature working?
No need to purchase, fully free.
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