LArge map projection?

[Naima]

HEllo , does anyone knows how could I do to make a large map projection? my map is 21kx10k and is the classic equirectangular, but the program I used to use for make the projection only accepts smaller sizes like 4k at max , so how can I do to project big maps?

Also eventually where can I upload a map that exceeds 80 mb and of the size above? I tried deviant art but doesn't work.

[Mouse]

Hello Naima

I've not even tried to answer any of your questions before as they have all been a bit too technical for me to understand properly, but it just occurred to me that a map size of 80 MB might indicate that you are possibly trying to upload a png file?

I don't know if that's really the case, but if it is, have you tried turning it into a jpeg and using about 8% compression?

[Naima]

Hi yes , but Deviant art refused as it said its over 200 megapixel wich I do not know what means.
it weights 79 mb .

[Mouse]

How big is it in terms of how many pixels wide and tall?

The biggest map I have ever uploaded here was 3500 x 2000, and it was a compressed jpeg file.

I don't know what megapixels are, other than my very old camera takes pictures that are 5 megapixel, and I think most modern cameras are about 10 megapixel?

I looked up the definition of a megapixel and this is what I got:

"a unit of graphic resolution equivalent to one million or (strictly) 1,048,576 (2 to the power of 20) pixels".

So by that reckoning my largest map was about (3500 x 2000)/1,048,576 = 6.6757202 megapixels, which is not much bigger than a 40th of the size of yours

Therefore - I really don't know what the solution is, other than to reduce the size of your image quite considerably.

....

EDIT: If the map is square (which I know its not, but if it was) then 200 megapixels would equate to:

The square root of (1,048,576 x 200)

Which would mean that the dimensions of the square would be 14,481 x 14,481 pixels, which is absolutely HUGE!

I don't know anything about DeviantArt because I don't have an account with them, but maybe a reduction in size to 25% or even 12.5% the original might work?

[johnvanvliet]

what projections do you need to convert it to ?

there is MMPS
http://www.users.globalnet.co.uk/~arcus/mmps/

i KNOW this builds using MinGW on windows

or GDAL

http://www.gdal.org/index.html

for a GUI to gdalwarp use Qgis
http://www.qgis.org/en/site/

[johnvanvliet]

14,481 x 14,481 pixels, which is absolutely HUGE!

not that big
i work with 32768x16384 and 65538 x 32768 pixel images

now HUGE is 131072 x 65536

[Azélor]

For people with normal computers, it's big.

[selden]

With less capable computers, you just have to be patient. That's one of the advantages of using scripts to manipulate images. You can start them up and continue to use the computer for other things (like browsing this forum) or let them run overnight. That's somewhat harder to do when you're using Gui-based software.

[Naima]

what projections do you need to convert it to ?

there is MMPS
http://www.users.globalnet.co.uk/~arcus/mmps/

i KNOW this builds using MinGW on windows

or GDAL

http://www.gdal.org/index.html

for a GUI to gdalwarp use Qgis
http://www.qgis.org/en/site/

I want to test several , but how do I use GDAL ? I do not like much to use command lin