# calculate x & y from lat & long

Discussion in 'MFC' started by answerme, Apr 29, 2010.

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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:
```[B]BOTTOM RIGHT CORDINATES[/B]
m_fMaxLat = 12.581369; //MAX lat value
m_fMaxLon = 77.383798;// Max long value

[B]TOP LEFT CORDINATES[/B]
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

2. ### chandu004New Member

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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