Random late night thought...
With the current UAS tech we can georeference hi-resolution imagery to a centimeter or so. The imagery itself can have GSD resolution down to a centimeter or less as well. With that said, whats the point of drafting linework in CAD on some projects when you can just show a current and high resolution image on the map? I'm not talking about engineering projects or where CAD files are really nessessary but say on a boundary or ALTA survey. We locate the buildings, things near the line, evidence, etc. with the total station and draft those things...but why trace in CAD all the peripheral stuff inside the property such as islands, walkways, striping, planters, water, and lots more that are easilly visable from the air. We're showing the imagery on our maps anyways and the image often shows more information than CAD lines ever could. I'm not suggesting this for every project but I keep looking at time sheets for CAD tracing and thinking its unnessesary on a fair amount of projects.?ÿ
Thoughts?
As stated, I feel each project has it's own requirements and in some cases tracing may be a viable solution but primarily, in my experience, more information is always needed further into the project, (ie elevations, a model, etc.) and you can't get that from tracing.
I've worked on projects where a boundary becomes an ALTA, that then becomes a re-sub, that then becomes a design topo and so on, just as an example.
T. Nelson - SAM
An ALTA survey is a perfect example of when you might want to trace a lot of features. Why pay a survey crew to locate parking stripes when you can easily trace them off the photo? I've seen the field time for an ALTA get cut by 75% by using a UAV. 1cm GSD and 2cm Hz precision are pretty easily achievable with a high end UAS.
@squirl When we fly with the UAS we also have point cloud data and elevation information can be easilly extracted at a later date if needed. Our last big project had an RMSEz of 0.03' on hard surfaces! Two birds with one stone...or is it two stones with one bird here?
@lee-d Why trace it in CAD when it'll be shown on the image underlay anyways?
Probably more habit than anything else, in our case.
@tomchurch I'm assuming that they want to be able to print a complete map without the imagery if that becomes necessary for some reason.