[OSRS-PROJ] Unknown USSR projection

[David Orme]

Hi,

Thanks to everyone for hints and help so far. Just to be clear, I have 
added the 10 degree lat/long lines - the only lat/long mark on the 
original is the dotted line of the arctic circle. The latitudes are 
centred on the best fit circle I could find to the the arctic circle 
curve and the longitudes radiate from there - they aren't perfect but 
they are close enough to suggest that the map is some form of conic.

Cheers,
David



On 8 Mar 2004, at 16:38, Gerald Evenden wrote:

> Looking at it with dividers and a ruler it looks to be a conic and 
> spacing
> of parallels eliminates equidistant.  The parallels are at 10 degree 
> intervals.
> but the longitude appears to be at 10 degree intervals as well but I 
> find
> odd discrepancies when comparing locations of the inland seas and
> arctic islands with an old Goode atlas.  Soviet disinformation, 
> maybe?? ;-)
> From what can be seen from the spacing of the parallels I would guess
> conformal so try Lambert Conformal Conic (lcc) as a first guess with
> tangential latitude near the center.  Scaling will be trial and error.
>
> PS: a lot of Soviet map projections are covered by Maling in "A Review
> of Some Russian Map Projection" in addition to the aforementioned 
> Snyder
> reference.
>
>>  I wondered if anybody can help me identify a projection. I need to 
>> digitize some range maps from a book on the birds of the USSR: all 
>> the maps share the same basemap but the book itself contains no 
>> projection details. The image is on the web: 
>> http://www.bio.ic.ac.uk/research/iowens/orme/FlintMap.png.
>>
>> The only latitude or longitude mark on the map is the arctic circle: 
>> as far as I can make out this is an arc from a circle, although there 
>> is a hint that at the edges of the map the arc may turn down away 
>> from the circle. I've tried identifying 10 degree lines of latitude 
>> and longitude from locations around the map edge and that suggests to 
>> me that the map is projected on something like a equidistant conic or 
>> albers projection. What I've got so far:
>>
>> * the central meridian is around 105 E.
>> * the longitude lines look like they converge on the centre of the 
>> circle, although if I try and draw them in from geography, they don't 
>> converge very well.
>> * a degree of longitude is about 0.4 degrees of arc on the projected 
>> map.
>> * the latitude lines don't seem to be equally spaced - in particular, 
>> the 80-70 N gap is wider than the other three latitudinal spacings.
>>
>> I can't get it to fit - has anyone got any suggestions for 
>> projections or projection parameters? It doesn't help that I suspect 
>> the map is rather inaccurately drawn.
>>
>> Thanks,
>> David
>>
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