Kristiania 1917 and Oslo Today

Aschehougs kart over Kristiania, 3rd edition, 1917 beside today's map, kept in step by a fit to 5 control points

1917 opacity Control points

1917 Aschehougs kart over Kristiania, 3rd edition, 1917

National Library of Norway, nb.no, public domain

Today Topographic map of Norway

Alignment

Aschehougs kart over Kristiania, 3rd edition, 1917 (Ivar Refsdal, 1:13 000, H. Aschehoug & Co.), from the National Library of Norway over IIIF. Today's map: © Kartverket, CC BY 4.0.

Control points from the Allmaps Georeference Annotation. A least-squares affine transform maps map pixels to web-mercator: 0.56 m per map pixel, rotated 0.88°, x/y scale ratio 1.015.

#	Map px (x, y)	Lat, lon	Residual m	Left out m
1	9307, 7660	59.91001, 10.77205	1.6	7.4
2	7982, 4287	59.92713, 10.75931	11.2	21.7
3	6210, 8581	59.90558, 10.74110	2.3	5.8
4	4782, 6407	59.91668, 10.72738	1.7	5.7
5	7848, 4437	59.92636, 10.75834	11.0	19.6
RMS / max			7.2 / 11.2

Residual: distance on the ground between a point's surveyed position and where the fit puts it. Left out: the same when the fit is made without that point. For comparison, the similarity fit 11.8 m RMS. The right pane is north-up; the left pane shows the sheet as printed.

Overlay and curtain draw the sheet with the closest rotation-and-scale fit (11.8 m RMS), because OpenSeadragon places an image by position, width and rotation only. Blue rings on today's map are the surveyed positions, so the gap to the printed feature shows the error.