Which CRS fits "Lambert Conformal Conic Projection, Standard Parallels 46.40 and 49.20"?

Question

I am trying to georeference a VFR chart in qgis and I can't figure out which CRS to use.

Map projection - Lambert Conformal Conic Projection, Standard Parallels 46.40 and 49.20.

Any ideas which one on the list will work?

Answer 1

If the chart shows US location, it's not using a state plane zone, and I can't think of another US-based CRS that has those standard parallel values (46deg 40min and 49deg 20min). With the knowledge that the chart's area of interest is in Canada, I couldn't find any existing CRS that match. I think you'll have to create a custom definition. The central meridian may be the longitude at the center of the map.

Here's a link to the QGIS 1.8 help on projections which discusses creating a custom definition near the bottom of the page.

I don't have QGIS to check this but there have been several other questions here about adding a custom projected coordinate reference system. Cribbing from one, here's a PROJ.4 line for a North American Albers definition:

+proj=aea +lat_1=20 +lat_2=60 +lat_0=40 +lon_0=-96 +x_0=0 +y_0=0 +ellps=GRS80 +datum=NAD83 +units=m +no_defs

Now let's modify it to match yours:

+proj=aea +lat_1=46.66666667 +lat_2=49.33333333 +lat_0=?? +lon_0=-?? +x_0=0 +y_0=0 +ellps=GRS80 +datum=NAD83 +units=m +no_defs

You'll have to fill in the lat_0 and lon_0 (latitude and longitude of origin, try the map's center?).