[Qgis-user] Qgis Map composer scale distorted in hard copy (printout)

[Andreas Neumann]

Hi Sashi,

First when I read your mail I thought - ok, this guy did not print out 
the PDF on  a 100% scale. Forgive me, but I lot of people ignore this 
option and then complain.

But your case seems to be a bit more complex.

What I propose is that you do not use EPSG 4326. Keep using your meter 
based projection and use a different CRS (e.g. EPSG 4326) just for your 
map grid. Since 2.6 (I believe), it is possible to define the CRS for 
the map grid separately and even have multiple grids on the same map. 
Please use this approach and see if it works better.

Getting a correct map scale for CRS 4326 (Plate Caree projection) is 
hard - since at every latitude the scale is different.

Hope this helps,
Andreas

On 01.06.2015 22:49, Sashikumar N wrote:
> Dear All,
> This is my first post to the forum as a new member. I seemed to be 
> jinxed by a scale distortion problem. I am using windows 8.1 version, 
> Qgis 2.8.1, installed as standalone version.
>
> Here is my problem, I am setting the scale in the Map composer as 
> 1:250,000 for a test print of A4 size sheet. i know the  straight line 
> distance of two points in the vector layers of map view. The distance 
> is 52.5 km approximately. For the above scale it means 1cm = 2500 m 
> (2.5 km). For the distance between the known points it should measure 
> as 21 cm in a printout. I exported the map composer sheet to pdf file 
> and then printed it. Now when i measure the distance between the known 
> points, it measures only 17.8 cm instead of 21 cm or the distance on 
> ground is calculated as only
> 44.5 km. So for the printed map, the scale is not 1:250,000 as fixed 
> in the map composer, but 1:295000
>
> While printing i have taken care that, auto scaling / fit to page etc 
> from printer setting is disabled. So i guess i print as it came out of 
> the map composer.
>
> My question in simple terms: does the map composer scale and printed 
> map scale match in a normal course? What is the mistake i am doing. Am 
> i ignoring the projection effects or any other basic criteria in 
> creating the map composition? How do i make sure that the scale in the 
> printout is same as the map composer scale?
>
>
> Thanks for your help
>
> ps: All my layers CRS is EPSG 24343 (Kalainpur 1975 / UTM zone 43 N), 
> I am using EPSG 4326 OTF to get lat long to be printed on the map. The 
> distance between points is measured horizontally across the map.
>
> -- 
> Thankyou
> regards
> sashi
>
>
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