B4J Question new Application

Pedro Caldeira

Active Member
Licensed User
Hello folks,
I am going to write a new application and want your opinions as to the best way to approach this.

Its going to be Linux App, probably to run in an Raspberry PI, or small pc.
desired Features:
connection to External GPS for better accurary
display of own coordinates on some kind of offline map or user defined window (using some user defined scale)
display of several points read from a DB that holds:
#name, #type,#lat,#long, #height from ground

the ideia is to display in the pane / map our own position (plane icon) and to show the relative position of the targets with distances to them, according to a scale (that can change at user request).
some kind of ground obstacle warning system for small aircraft.

With the google maps library, is not hard to do this, as we only have to set some markers with the given coordinates. But i don't want to be dependent on internet, either GSM,
4G or whatever.
just the GPS, an internal DB and calculations ;)

I has thinking on using a pane and to create some kind of user scale to match the coordinates of the targets and my own position onto the pane, with their relative distances and offsets.
any ideas ? What would be the best approach ?

Regards,
 

MarkusR

Well-Known Member
Licensed User

Pedro Caldeira

Active Member
Licensed User
u can export images here from www.openstreetmap.org
read this manual, there is also a link to the export page
https://wiki.openstreetmap.org/wiki/Export
u need click the share button and then put this image into a sqllite blob field with the location info from-to /scale etc.
i used this tool for sql lite databases
http://sqlitebrowser.org/

a simple lat/log format is a decimal value with ~ fractional 8 digits in degree°
Thanks MarkusR. I will sure take a look
 

MarkusR

Well-Known Member
Licensed User
if u use ui elemente like image/button/label u just need to set the position, else u need paint all manual.
degree to screen coords are a simple formula.
i guess your external gps data comes in via serial input stream, should be like an plain text file.
local database access would be jSQL lib comes with ide.
 

Pedro Caldeira

Active Member
Licensed User
if u use ui elemente like image/button/label u just need to set the position, else u need paint all manual.
degree to screen coords are a simple formula.
i guess your external gps data comes in via serial input stream, should be like an plain text file.
local database access would be jSQL lib comes with ide.
I will prob use a small image for the markers, yes.
But how do I display the openmap in, for instance, a pane ? its not a image format, it donwloads a xml file ?
And the data from the GPS wlll be a NMEA sentence, and yes via RS232.
My ideia was for the DB to only store plain text, descriptions and coordinates.
the map would be used to display a base map, and to have a visual geographic reference to display the markers.
 
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