In 2006 when I got my Leica 1205 with Carlson SurvCE on a Allegro controller, I switched to shooting building wall planes in reflectorless mode. I code the wall shots as a BPT which is set to a NOZ style and the controller automatically switches the rod height to 0 feet. I usually take double shots for each point on the building wall line to verify I'm getting the same point on the wall and not o twig on a tree.
I always shoot through clear openings.
When I get back in the office, I connect the 3 or 4 shots on the wall plane in CADD and check the offset from the middle points to the line connected to the two end points. Usually it's 0.01 or 0.02 depending on the type of wall surface like siding, brick or block or solid concrete.
The key is to shoot the same line (from a height perspective) along the wall line as possible.
If setback is critical, I'll include gutter shots as well.
I also tape or laser shoot the wall lines with my Disto as a check against the intersected wall lines in CADD. We are still walking around the buildings and measuring the wall lines, but it is for checking purposes for the most part. Once in awhile, there is a jog or something out of the ordinary that needs a tape, ruler or laser.
In the case of collecting the ground shot elevation at the building corners during a topo survey, I usually just take a ground shot opposite the major corners or if the building is exposed and there is a breakline involved, we just pick up the breaklines as well.
First, let’s stipulate that seldom does a building corner represent the building line. The corner is usually rounded, warped, or otherwise so uneven that it is best to shoot two points about a tenth or so back from the apparent corner, then later prolong the lines to get a representative corner.
With GPS I use a distance-distance intersection with a Disto, and the rover on a bipod for a steady shot. My F2F program automatically solves for the corner. If I’m going clockwise I code it DD, and if counter-clockwise the code is RR.
200 BK DD 10.21
201 BK DD 10.78
With reflectorless I put a strip of masking tape on the wall and a dot 0.10 feet from the perceived corner. I take a shot back along the line using a code CC, then a shot on the dot and code that CC.10. The F2F program automatically prolongs the line 0.10 feet and solves for the corner.
202 BK CC
203 BK CC.10
For mobile homes, which are often difficult to approach and don’t require great accuracy, I have a routine that uses the code KK and five offsets in line but no distances. The program uses the lines to automatically draw the mobile home.
204 B KK
205 KK
206 KK
207 KK
208 E KK
As I previously mentioned, the building line extended shots at arbitrary distances, and then just intersect the lines in CAD provides excellent results. Just code them right or you'll be all confused.
Then draw your tape measured building at 90 deg, and place it within those intersection points. You'll see a tenth here & there, but.....
Also, kinda suprised nobody brought up the topic of facia, siding, foundation, etc.
A very handy little tool is a 60d nail. It is 0.5 feet in length, a convenient offset. Place it against the wall such that you can place the prism in line with the intersecting wall and 0.5 feet offset, using the nail to verify the point you are shooting.
Instruct the rodman to place the prism so that it measures the DISTANCE to the BC; shoot the distance then turn the crosshairs to the actual corner and then store the shot. I usually also shoot a couple building face shots reflectorless for redundancy.
Hmmm...no one mentioned a dual prism rod, which is quite accurate. You can place the tip of the rod wherever you want-at ground level if needed, or hold the rod horizontal
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> Hmmm...no one mentioned a dual prism rod
No mention of "The Scanner" either. Just set the dang thing up and hit he button...
😉
Dugger
Link to the dual prism pole?
I understand how it works, but what software does the calculations?
Most DC software should have an offset routine that will allow you to locate two points and give an offset along that line to the actual point.
> A very handy little tool is a 60d nail. It is 0.5 feet in length, a convenient offset.
A new trick. Nice.
> Most DC software should have an offset routine that will allow you to locate two points and give an offset along that line to the actual point.
Hmmm...in 3d? I don't think my Leica Viva or the old TSC does that.
I've used the method to tie a snookered boundary corner and it worked very well, but I calc'd it using 3d points and lines in autocad.
well, for one thing Survey Controller (Trimble) has it built in. I imagine others do as well.
But, because I messed up on a job recently, and took 100+ shots with the wrong prism offset, I had to manually compute all of the shots from the data in the TSC job file. Well, not manually, I created a program to do it. Going back to reshoot the points was out of the question.
I had forgotten that one; thanks for the reminder.
KS
Poor assumption on my part. For what it's worth, both TopSurv8 and SurvCE both have hidden point routines that would be suitable for use with a two prism rod.
Thanks for mentioning the article, John. I know I didn't come up with the method, but it was a lot of fun teaching it to myself and then getting a chance to write about it. It still amazes me how precise this type of offset can be.
I measure 1' offsets on line with the walls using a tape measure and then draft the buildings in the office. Taping the building in the field and sketching them on large clip board really helps. When drafting the buildings you have to use some judgment regarding holding the building as figure with neat right angles or fitting it to the measured points.
When running a robotic instrument from the rod it is very difficult to line up accurate right-angle offsets using the data collector, so I use manual offsets with a tape.
Even though the ALTA/ACSM standard requirements state that the buildings are to be measured "at ground level", I have found that many of the buildings that I locate on land title surveys have complex shapes that are better represented at some point above the ground. I put a note on the plat stating where the measurements were taken if the building is near a property line or easement.
> well, for one thing Survey Controller (Trimble) has it built in. I imagine others do as well.
>
> But, because I messed up on a job recently, and took 100+ shots with the wrong prism offset, I had to manually compute all of the shots from the data in the TSC job file. Well, not manually, I created a program to do it. Going back to reshoot the points was out of the question.
>
In Survey Controller, I've shot many points while forgetting to change offsets or rod heights. If you know the points that are in error, make a simple edit to your file. Go to Menu, Review Current Job. Scroll to the first point in error. Hit the plus next to the point. You will see a line for whatever Target you were using. Tap this line and edit accordingly. When you hit OK, the target information has been changed for that point only. Immediatly following that point information, under Review Current Job, a new line will have been added for Target information. This information in this Target line will be for all of the following shots and will be the same (incorrect) information you are needing to change. Tap this Target line and edit like you did previously. Now the target information has been updated for all of the following shots in the DC file. All of the coordinates have been updaded, and there is no need to edit any further.
FYI, I think in the older versions of SC, instead of little pluses next to the points, there was a "+Target" box you could hit while reviewing the job that did the same function.
I like a 30-06 to shoot them with, you can always go back later and find the mark. If you shoot only the downwind corners and measure the rest, little water will leak into the structure if there are good gutters in place.
jud
Actually I will turn the angle to the corner, then use the mini prism rigged for plum bob use so the 30 MM offset is marked with a slot line and line it up with the corner with the prism pointing at the gun and shoot the distance. Do the same using a full sized prism using the rod or the sighting plate aligned with the corner. Only use offsets if the corner is not visible from the gun and then I often use the plumb bob to locate the point on line. Yep, the plumb bob is on my belt along with the 25 foot tape.
jud
Different gear gets different procedures. Reflectorless gets the building at the corner and interior corner. For those corners where the angle of incidences is poor, I use the Paul method of collecting a few points on the face and taping it.
For conventional, the reflector is placed beside the building corner, at 90° to it and facing the instrument. This is easily achieved by using the center of the bracket for the prism. Then the distance is recorded, the angle turned to the corner, and the angle recorded.
Regardless of whether or not I use reflectorless or not, all buildings get strapped in their entirety, and the building is checked for square before leaving the field. Houses with window seats and other crazy offsets require a little "eyeballing" with overall distances and the legs of the right triangles out, but it's all shown on the detail so that it can be calculated in the office.
In the drafting, shots taken are checked against distances taken and I very seldom see more than a few tenths different, and that is generally due to the age of the house (falling in) or a house that isn't square (I know it before I leave the field) or different types of material (like brick to rock to hardy plank).
Some houses, you can't make square, so I do a best fit with rotation and let it roll.