Several commercial software vendors, including Mentor Software, have published software products which provide more intelligence to the conversion process. In particular, they add the ability to control color, line style, layer, etc., as well as convert areas as closed polygons, etc. For example, Mentor Software's product (now called Marinus) will produce either .DXF or .DWG directly from the DLG, perform coordinate conversion during the format conversion process, and provide such other nicies; such as distinguishing between section and township lines (in PLSS data) and labeling sections and townships.

There are several other vendors which have similar type products, and the price ranges go from $99 to over $1,000.

Pretty much all of the above equally applies to Shape files, DRG files, MIF files, etc. Some of the more expensive products claim to be able to do all of them in one package. For example, check out the products of Safe Software.

If you only have a small region to do, I usually recommend that you purchase the map data already converted. For example, ADCI, Micro Map & CAD, or WhiteStar can provide you with the maps already converted at a reasonable price. I would not consider licensing any of the commercial packages unless I had a whole lot of real estate to convert, i.e. a minimum of several counties.

Hope this helps.

Norm Olsen

Dave Gibbon
http://www.panthersoftware.com

In the standard two parallel case, in addition to specifying the standard parallels, you usually get to specify the origin latitude separately. In this case, all the origin latitude does is specify the latitude at which the northing/Y is zero (before application of a false northing if any).

In the single parallel case, usually you just specify the origin point.  The latitude of the origin point serves as both the standard parallel and the origin latitude. Thus, you get a little bit less flexibility with the single parallel case. As indicated above, you can use the double parallel case to reproduce the same results as the single parallel case by simply setting all three latitudes to the same value. However, folks like to see what they are used to, so we have introduced a variation which will accommodate their needs.

If you are trying to duplicate a system defined in Landmark, simply use the variation which they use. Perhaps they use the technique of simply setting both standard parallels to the same value. This will work fine in CS-MAP.

Hope this helps.

The idea behind two parallels is that the projection surface (i.e. the cone in this case) is shrunken into the earth so that it enters at the first standard parallel and leaves at the second. This has the effect of distributing the distortion generated by the projection more evenly across the map, and reduces the largest amount of distortion.

The single parallel version of the Lambert Conformal Conic achieves this "shrinkage" affect by using a scale reduction factor. This, so to speak, just shrinks the cone by a certain percentage, and mathematically achieves the same result as the double parallel situation.

If one were very smart, one could figure out exactly what specific standard parallels would produce the same shrinkage effect as a scale reduction factor. Most of us are not capable of doing that. Therefore,  I must say that in the case where the reduction factor is not 1.0, it would be difficult to use the two parallel variation to accomplish this.

CS-MAP does support the single parallel variation, with scale reduction factor. The name you would use in the COORDSYS.ASC file is "LM1SP".

You could also use the Lambert Tangential, "LMATN", to achieve the same result. Lambert Tangential is the term preferred (I believe) by the French.

Let me make an educated guess as to why the results seem strange, keeping in mind that my education in these matters was obtained from the school of hard knocks. (I'm a computer programmer by trade and education.)  The traditional "forward" and "inverse" calculations are based on a geodesic (i.e. the ellipsoidal equivalent of the spherical great circle). That is, the latitude, longitude (of the 1st station) and the provided azimuth define a specific geodesic. If one proceeds 49.23 nautical miles along this geodesic, the resulting position is that which was provided by FwdInv. A geodesic does not, usually, follow a line of latitude unless that line of latitude happens to be the equator. If you change the latitude of the first station to zero, you will obtain results which are more comforting.

Hope this helps.