# Changing Pixel quanty to hectares on a 1:10000 map

• May 19th 2011, 04:22 AM
ninton
Changing Pixel quanty to hectares on a 1:10000 map
Hey,

I just had a question regarding changing a pixel quantity to a unit of measurement.
Previously, on 1:50000 maps, to change the number of pixels to hectares I multiplied the value of pixels by 0.25, because one pixel was 0.25 hectares. The data I was using was a 50m Digital terrain model, 50*50=2500 which = 0.25 hectares

Now on a 1:10000 map, Im unsure of what to times the pixel value by to get a value in hectares. The model is a 10m, so 10*10=100, so i should times my answer by 0.01 right? but that doesnt give the value I want, is that correct though?

Thanks
• May 19th 2011, 04:47 AM
emakarov
Quote:

Now on a 1:10000 map, Im unsure of what to times the pixel value by to get a value in hectares. The model is a 10m, so 10*10=100, so i should times my answer by 0.01 right?
That seems correct.

Quote:

but that doesnt give the value I want
What value do you want?

When you were using 1:50000 maps, you say that 1 pixel on the screen corresponded to 50 m on the terrain. Since 50 m = 50 000 mm, this means that 1 pixel on your screen takes 1 mm, which is too much. A typical screen resolution is 96 pixels/inch, which is about 3.8 pixels/mm.

Could it be that you are using different zooms to show maps on your screen?
• May 19th 2011, 04:53 AM
ninton
actually, ive just realised what i was doing was already right and i was just overcomplicating it. thanks for your help