Model Space Scale Issue

[jdelashmitHMLTW]

Just started using Maps, I noticed that the scale in model space isn't 1-1 like regular CAD, but also changes as I zoom in and out. This is causing some issues with my dimensions and measurements, not to mention making it difficult to be precise in my drawings. Is there a reason why its like this, and is there a way to make it 1-1 like in regular CAD?

Thanks in advance

[ChicagoLooper · Accepted solution]

 @jdelashmitHMLTW 

It is like regular CAD.

I suspect you are drawing in inches, correct?

In vanilla Cad, if you draw a circle with radius of 12 (twelve), you'll end up with a circle with Radius of one-foot, or a Diameter exactly 2 feet. There isn't anything wrong with radius=12 especially if you're drawing in vanilla Cad with units of inches.

In Map 3D, however, you're drawing in feet and that means to draw the same sized circle you'd input a radius of 1 (one) and end up with a circle with Diameter exactly 2 feet.

The million dollar question is How do you draw a circle with a Diameter=2? Do you draw one with radius=12 or radius of 1? 

Furthermore, in M3D, if your want your circle's centerpoint at coordinates at 1000,2000 which is 1000-ft in the X direction and 2000-ft in Y direction, then your circle's centerpoint will be x=1000 and y=2000.

On the other hand, in vanilla Cad, if you want that same circle to be at the same geospatial location on planet Earth, then those coordinates would be 12000, 24000. Why? Because x coordinate of 12000 inches=1000 feet and y coordinate of 24000 inches=2000feet.

You are not alone. The 'drawing units' play a vital role when dealing with geospatial locations and this confuses many vanilla users when they switch over to M3D. Geospatial entities like the north pole, equator, objects drawn by coworkers or collaborators, and the georeferenced data you download and use all contribute to your map. If you're going to draw in Map3D, then you'll need to adjust to feet because the entire geospatial world uses feet (or meters), not inches. If you still insist using inches, then you can use vanilla Cad (or Revit) where it's more conducive to inches.

[jdelashmitHMLTW · Accepted solution]

So in other words, Maps only works using Decimal Units? 

[ChicagoLooper]

Map3D will WORK with any units you want. You don't necessarily have to assign a coordinate system but if you choose not to then what's the point in using a geospatial program like Map3D in the first place?  

Map 3D is specialized for geospatial work where your modelspace has an 'Assigned Coordinate System' and that means the units will be feet, meters, or degrees. Why? Because the drawing units will adopt, or inherit, the coordinate system's native units. Since there aren't any coordinate systems that use units of inches, you're relegated to using a CS that has feet, meters, or degrees, NOT inches. Never ever inches.

You could make the argument that you don't want to assign a coordinate system so you can use inches instead of feet, but that'll be a poor argument because the whole purpose of using M3D is to assign a CS so you can be geospatially oriented to the north pole and equator. And to be correctly oriented to Planet Earth, you'll need a coordinate system.

Besides, if you properly assign a PROJECTED coordinate system to modelspace then you'll be able to turn on Bing Aerial Imagery and use it as a basemap. In addition to Bing you can also build a map by adding roads, streams, topographic contours, state border lines, and surveyed points you or a coworker acquired using a handheld during field work. The list goes on. As long as your 'added-linework and objects' are accurately georeferenced, they'll plop down in modelspace accurately because you assigned an appropriate CS. Y'know, that CS that uses either feet or meters, not inches.