Go4Expert - calculate x & y from lat & long

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calculate x & y from lat & long

I am getting GPS data on my window
Actual GPS DATA is stored in these 2 variables

Code:

float landlong= 77.384547E //Realtime Longtitude

float landlat = 12.583857N   //RealTime Latitude

But it seems the lat & long which iam getting from GPS is not coming inside window, its out of window .I checked x & y cordinates it is

Code:

xPos = 1415.7537                

yPos = -167.81079

the width & height of my window is

Code:

m_WndWidth=1099

m_WndHeight=673

The formula which iam using to calclulate x & y cordinates is

Code:

xPos = (landlong - m_fMinLon) * (m_WndWidth / (m_fMaxLon - m_fMinLon)) ;

yPos = (landlat - m_fMinLat)  * (m_WndHeight / (m_fMaxLat - m_fMinLat)) ;

Code:

BOTTOM RIGHT CORDINATES

m_fMaxLat = 12.581369; //MAX lat value        

m_fMaxLon = 77.383798;// Max long value



TOP LEFT CORDINATES

m_fMinLat = 12.583361;//Min lat value        

m_fMinLon = 77.381506;//min long value

Does anyone has the proper formula to calculate X & Y cordinates

Thanks in advance

Re: calculate x & y from lat & long

your formula seems to be alright. but your point is getting displayed beyond the screen display area. to solve this, you need to map (or scale in other words) the start and end co ordinates of your map with your display area, and also you should scale every gps point you are displaying wrt the screen co ordinates.
long back, i also faced the same problem, and i solved it this way.
feel free to mail me, for any further queries.
chandu004@yahoo.com