Having an issue with drawing units and scaling when drawing over a geomap.

[bareyan]

Hi there,

I'm having a hard time figuring out what is going on. Currently, we have plans in decimal units. When drawing over a geomap, everything appears scaled and correct. However, I wanted to change the drawing units to engineering (0'-0") so that we have accurate drawings and draw with ease without having to convert every measure to decimal feet. So once I changed to engineering units, with insertion scale set to inch, all of a sudden everything is measured in the unit of inches. So my sidewalk that is for a fact, 6 feet is now shown as 6 inches. And I can't figure out any way to change what unit that is measured in. Also, stationing that is typically (and was previously shown) at 100 feet now measures at 8'-4" (which is 100 inches instead of 100 feet). I tried changing the insertion scale to feet and it doesn't work. I've tried to find answers on this and I can't figure it out. I don't know if it's a geomap scaling issue or if it's some how my drawing units but the only possible way I can even get halfway to what I want is to change the dimstyle to engineering with a scale factor of 12 and that forces the dimensions to now show as the correct ft-in. This feels like a lazy work-around and I feel like there's got to be a way to tackle this at the source and have my lines accurately draw to scale with respect to the geomap. This way I can just input ft-in when drawing a line instead of converting to decimal. Any help would be much appreciated. I'm more or less trying to renovate our autocad files to have a uniform drawing scale, units, etc. so we have a clean template to go off of. Sorry if this was at all confusing, I'm having a hard time even describing the issue. Thanks again for any help.

[ChicagoLooper]

HI @bareyan 

Engineering drawing are always drawn in units of FEET. Architectural drawings, as an example, are always drawn in units of INCHES.

If you have a drawing with a sidewalk that is really 6 feet but now only measures as 6 inches, then you have a DRAWING UNIT issue and you're struggling to make it work. And to compound your issue, you are also trying to draw over Bing aerial imagery which has a geographic projection (EPSG 4326) that uses Lat/Longs with units of degrees. You are allowed to assign State Plane-Zone-Feet to your drawing so Bing imagery can re-project from its native degrees to your drawing units of feet, but keep in mind, your specific situation also introduces another drawing unit (inches) from another (architectural?) drawing.

If you want to effectively work with georeferenced drawings and geospatial objects that you acquire on your own or receive from others, you should abandon drawing units of inches and draw exclusively in feet. If you fail to accept feet then you'll have issues (big time issues) when working with geospatial objects and Bing imagery.

Whether they're georeferenced images, shapefiles, geodatabase, surveyed points or lines, your geospatial drawing units will always be in feet, never in inches. Alternatively, you may also work with drawing units in meters. Feet and meters are the typical Drawing Units in Georeferenced Drawings and their 'assigned coordinate systems' will have units of feet, meters, or degrees. Never inches, centimeters, or millimeters. Never, ever.

When used properly, Map3D can insert, scale, and position objects accurately, on its own, as long as you have properly assigned an appropriate CS to your drawing AND you honor the native CS of the objects you wish to insert. If you fail to assign a CS properly or ignore the native CS of inserted objects, you'll have issues.

You can't turn on Bing Maps and expect your objects and vertices to always conform to the imagery. Those objects must to be drawn using feet. For example, a 6X4 rectangle in an 'inches drawing' will be 6-inches wide by 4-inches tall. While a 6X4 rectangle in a 'feet drawing' will be 6-feet wide by 4-feet tall. However, if you drew a rectangle 72-inches by 48-inches in your inches drawing, that same rectangle, when inserted, would be 6-ft wide by 4-ft tall because it's already scaled by a factor of 12 when moving from an Inches dwg to a Feet dwg. 

Do not change the drawing units, keep the drawing as feet, then SCALE all your objects to fix it. Be sure to enter 0,0 as your basepoint and use a factor of 12 so your objects will convert to feet. You may also need to MOVE all your objects from their non-georeferenced location to their TRUE geospatial location after you've scaled.

Why must you SCALE? You must scale because all georeferenced drawings must have units of feet or meters. (The only exception is using units of Indian Chains, and I've never seen, used, or heard of a drawing that uses Indian Chains. I think Indian Chains, whatever its length, went out-of-style the same year as the abacus.)

No matter how hard you try, you can't SCALE Bing imagery to match your objects, you must SCALE your objects to match Bing.

If you are willing to share your drawing, a more relatable workflow can be provided. If you are unable to upload your actual drawing, you might consider uploading a sample of your drawing.

[Pointdump]

Hi Benjamin,
There's no way to fix your drawing. Civil 3D and Map 3D won't tolerate inch units.
Dave