Hi,
Please, look at my answers (in red color) below:
Thanks!
--- El mié, 22/12/10, Don Dietrick <dfdietrick_at_gmail.com> escribió:
De: Don Dietrick <dfdietrick_at_gmail.com>
Asunto: Re: [OpenMap Users] Re: Problem with OMArc
Para: "Ruben DF" <rdocasalf_at_yahoo.es>
CC: "openmap-users_at_bbn.com" <openmap-users_at_bbn.com>
Fecha: miércoles, 22 de diciembre, 2010 23:48
The OMArc just forwards the projection request to the Projection object - that object is responsible for using the spherical model for those points. Updating the OMArc would take some work, but you could override the getCoordLists function to do it.
I've been finding out something about GreatCircle at Openmap forum. I've realized (in a post of january 2002) that you migth have the Ken Anderson's GreatCircle class based on an ellipsoidal model (because I'm afraid it has not been integrated yet from what i've seen). If you still have that code I'd really appreciate it :)
To make the arc smoother, you should be able to increase the number of points are using. Your algorithm and the projection's are basically the same, it sounds like it's using more points than you.
I'm really using the algorithm of openmap. Specifically I'm using arcCalc.generate(p1.x, p1.y, p2.x,p2.y) in order to get the points between the ends of the arc. With those points I generate a OMPoly. I was trying to increase the number of points by means of increasing the variable numPoints (of generate method) and decreasing the angleIncrement. However, points (x,y) retrieved are very similar and its conversion to lat-lon are the same, so I almost have the same points.
Hope this helps,
-- Don
On Dec 21, 2010, at 11:56 AM, Ruben DF <rdocasalf_at_yahoo.es> wrote:
Don, thanks for answering.
I was trying to get the points generated in arcCalc between two points and rendering them into OMPoly class (using inverse method). With this I have more accurate (Ellipsoidal mode) between the ends of the arc but this one seems like has a few points (about 300 points) therefore the arc generated is like "pixeled" (with peaks), instead of OMArc, which is generated in a smooth way...Is there anyway to change OMArc to use ellipsoidal mode instead of spherical mode?
Thanks again
--- El vie, 17/12/10, Don Dietrick <dfdietrick_at_gmail.com> escribió:
De: Don Dietrick <dfdietrick_at_gmail.com>
Asunto: [OpenMap Users] Re: Problem with OMArc
Para: "Ruben DF" <rdocasalf_at_yahoo.es>
CC:
"openmap-users_at_bbn.com" <openmap-users_at_bbn.com>
Fecha: viernes, 17 de diciembre, 2010 02:30
Hi Ruben,
My guess is that the OMArc calculations are based on a spherical model of the earth, and Geo works on an ellipsoidal model (and is more accurate). That's probably why the difference is greater as you move away from the equator, since the models diverge the same way.
I've used the Geo class to create points for an arc, which I then sent to an OMPoly for rendering.
Hope this helps,
-- Don
On Dec 15, 2010, at 12:45 PM, Ruben DF <rdocasalf_at_yahoo.es> wrote:
Hi,
I'm having some troubles with OMArc component. Imagine I have 2 points drawn on the map (A and B, for example) and I want to get the arc between both of them (common case). First of all, center of both points is calculated by means of midPoint method (from Geo class). Afterwards, having center point, I can calculate the distance and azimuth between one of the points (A for example) and the center (with distanceKM and azimuth methods respectively from Geo class) The problem is related to generate the OMArc, since this appears slighlty moved, I mean, It seems that the azimuth between center and A does not match up (this effect is higher when I zoom the map in) and
because of this, there is a short distance (several meters) between point A and one of the end of the arc.
Any ideas?? any help will be appreciate.
Thanks in
advance
Regards
Ruben
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Received on Wed Dec 29 2010 - 06:48:39 EST