Hi guys
I'm starting on a construction job soon where there'll be a lot of setting out. I've done a few of these before and I've used a combination of the original survey stations and a few reflective targets for resecting.
I was taught that when shooting in reflective targets to be as close to 90 degrees as possible to the target, shoot face left and right and to try and shoot it from more than one primary control station.
Are there any other best practice tips for shooting targets? Does the distance matter?
Regards, Andrew
You need to be very close to 90?ø from the reflective sheet to maintain accuracy. This restricts their usage. Recently prefer using magnetic sphere prisms (shown below). If the surface is not magnetic, they have a center hole under the sphere which allows for mounting on wood or concrete with a screw. They can be rotated 180?ø from the horizontal plane (when mounted to a vertical column) and 360?ø in the vertical plane. I will outline the base of the magnet on steel column to assure location. These are 1" prisms with -22.5mm P.C. These prisms work much better than sheets, with robotic TS.
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When adding control to floors at pre-concrete, there is no way to stabilize a tripod on the metal corrugated deck. Therefore we use column clamps. The sliver clamps below are custom made by the local plumbers. All trades on this project have robotic Total Stations for layout. We also place prisms on adjacent buildings for control points.
I am using reflective sheet targets every day with pretty consistent results with 2 face readings. I believe the key to accuracy is to set them far?ÿ outside your site in such way that no matter where you are setting up the angle between the telescope axis and the face of the sticker does not change much. When I read a sticker in a resection at a small incidence angle I usually read it "Angle Only" . Another rule I?ÿ apply as much as possible is that the sticker should be affixed to a flat surface. When you're setting them on round light poles, use a smaller size sticker so that the curvature of the sticker won't influence much the distance readings. I am always using the Reflectorless mode with my Geomax Zoom 90 and I?ÿ get consistent distance redings to?ÿ little over 300m?ÿ At that distance?ÿ I am using 90mm targets. All this being said, Lee's 360 prism control setup is much more elegant. If you use something like a Leica TS16 that can ignore control prisms when power searching , you should be ok. My Zoom90 would lock on every prism in its path. A Trimble robot with an active prism at the pole would probably be a good option as well.
That??s all good advice. Especially the part about perpendicular.?ÿ
ive run lots of traverses on tall stakes. Finish nail on top. Pinch of dot tape. Closed with near perfect closures. If you make targets that are rotatable (rotate it to face the inst) it works well. Also, keep target size small, especially on short shots. (Short shots, not very perpendicular, small pinch of tape)
ive not looked through an instant in over 5 yrs!!
kinda miss it.?ÿ
n
One tip I learnt here...
If you are using the stick-on targets - mount them like a diamond?ÿ - ie put a vertex not an edge uppermost.
Makes finding the centre easier, particularly from a distance.
Great advise guys - thanks for posting. Love the 360 prisms, love the angle only top.
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