5 replies to this topic

[anael]

Hii
I have an old scanned map
I want to check its accuracy in GIS (Arcmap) Before doing regisration or georeferencing
it is possible?

I hope you can help me to do thes
Waiting for an answer


anael

[Sab]

Does it have a scale bar?

For geo-referencing, you can follow this:

[Hans van der Maarel]

Generally speaking, you'll need to know the scale and projection of the map. If you don't, you'll have to go through a lengthier process picking more control points. What software do you have available?

[isabella]

I have the same situation too. That's why I look for a forum like this.
Is it still accurate to use old scanned map? Or, should I use a newer one?

And what software are available for control points?

Thank you very much.

[Matthew Hampton]

I would suggest looking into MapAnalyst by Bernhard Jenny. It purports to check "the accuracy analysis of old maps. Its main purpose is to compute distortion grids and other types of visualizations that illustrate the geometrical accuracy and distortion of old maps."

I've never used the software - but if it's similar to any of his other software - it should work with aplomb.

Best of all - it's Open Source.

[GIS xtra]

What kind of accuracy is looking for ? is a large scale or small scale. If the map prepared in large (source) scale and printed/plotted in small scale, the accuracy may decrease during scanning /georeferencing/digitizing (eg. prepared in 1:50,000 and plotted in 1:100,000).