<br>Hi Martin,<br><br>Thanks for reply......<br><br>>But in case you have to transform just of some data, it's possible<br>
>that your data might be incorrect.<br><br>What does this mean ??<br>Actually the shapefiles I am using is downloaded from ibcca.<br>And over though, how QGIS is rendering it properly ?<br>Did u mean that I have to do coordinate Transformation on features before they are drawn ?<br>
Actually I want to know that how QGIS is able to draw the shapefiles correctly and not my application ?<br>Is there special code for this since the way QGraphicsView is created is same in QGIS and in my application.<br><br>
Thanks <br>bargi<br><br>
<font color="#888888"><br></font><br><div class="gmail_quote">On Sat, Jun 21, 2008 at 4:34 PM, Martin Dobias <<a href="http://wonder.sk">wonder.sk</a>@<a href="http://gmail.com">gmail.com</a>> wrote:<br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
<div class="Ih2E3d">On Thu, Jun 19, 2008 at 6:43 AM, bargi john <<a href="mailto:bargi1981@gmail.com">bargi1981@gmail.com</a>> wrote:<br>
> Hi Martin,<br>
><br>
> Thanks for reply......<br>
> Actually the application I am working on is similar to QGIS in which<br>
> shapefiles are rendered using QT.<br>
> In between, I researched on the problem and find out that this issue is<br>
> related to QGraphicsView architecture.<br>
> In essence, when QGraphicsView is created , it create with origin(0,0) at<br>
> top left corner. Due to which the positive quadrant is downwards and<br>
> negative upwards ( What I think ) due to which when shapefiles are rendered<br>
> according the coordinates position they draw in downward direction( because<br>
> coordinates of shapefiles are positive) and they appear to inverted.I found<br>
> scaling as a clutch which invert the the GraphicsView and line and polygon<br>
> shapefiles are drawn properly but it invert the point shapefile.<br>
> Due to this I reached to the possible solution that can be applied on<br>
> application:-<br>
><br>
> --- One way can be that we create the QGraphicsView with origin(0,0) at<br>
> bottom left corner.Due to this we will get the proper coordinate system for<br>
> rendering. I have tried on it but not able to find the sol. how it will be<br>
> implemented.<br>
<br>
</div>Actually, coordinates can be both positive and negative: with<br>
unprojected coordinates on earth:<br>
- x in range [-180, 180]<br>
- y in range [-90,90]<br>
<br>
northern hemisphere: y positive<br>
eastern hemisphere: x positive<br>
<br>
But in case you have to transform just of some data, it's possible<br>
that your data might be incorrect.<br>
<font color="#888888"><br>
Martin<br>
</font></blockquote></div><br>