Site Measuring Revisited Again

[Andrew Garulay, RLA]

I’ve put up a couple of discussions in the past regarding tools and methods for site measuring to supplement a survey or for a small project. Back in November I saw the video below and decided to buy the Disto S910 because of its ability to export a dxf file that I can import into a dwg. I find it extremely helpful for accuracy and saving time when supplementing information on a site plan.

It is not a survey instrument and has plenty of limitations, but it does what it does very well. It can’t be used for layout for example. It does a great job locating points and their relationship to each other with x,y,z coordinates connected by a polyline connecting them. It will also take a photo of what you shoot with crosshairs on the point that you located – excellent for saving you from having to take a ton of notes. 

I’m finding techniques and methods to get the best use out of it for what I want to do with it. I spent 45 minutes on a site on Friday getting 82 points and then was able to draft up a complete base plan for a conceptual pool plan in just under an hour when I got back to my office. Normally it would have taken about 2 hours to measure (with far less accuracy) and another two to draft. I’d also have to go back to field check and take other measurements for verification.

If anyone is interested in this, I’d be happy to try to answer your questions as best that I can.

https://www.youtube.com/watch?v=xWX7PVToYs0

https://lasers.leica-geosystems.com/disto/s910?gclid=CjwKEAiA9s_BBRCL3ZKWsfblgS8SJACbST7DgQMN3NrH7EiQm3t4tOAKmz_hJQ9aRoWX6LR9y3XwJRoCf2nw_wcB

[Cheryl Corson]

Sounds great. I have a Ziplevel. How does it compare?
Cheryl Corson

[Andrew Garulay, RLA]

I also have a ZipLevel. It is totally different. One does not replace the other. I still use the ziplevel to get very specific elevation differences.

I use this Disto tool for accurately locating things in relation to other things – usually to something that is already in a plan or in a cad drawing such as a building. The device is a laser range finder (or distance meter) like many others, but has extra capabilities. The big difference is that when you put it on a tripod it can also keep track of the vertical and horizontal angles with those measurement and mathematically calculate those points in three dimensions. It also has the ability to store those and make a dxf (AutoCAD file) with those points and a polyline that connects them. Each point has text associated with it that has the number of the point in the order that you located it, exact time and date of when it was taken, and the file name of the photo the device took of the point as it was being shot so that you can see what it is.

I set it up, take my first shot at the bottom of the siding or top of foundation of the left side of the building as I’m looking at it. That gives me the reference point that everything that I shoot will be compared with (it becomes 0,0,0 in the dxf file). The next point that I shoot is usually somewhere on the right corner of the same building so that I can use the first leg of the line connecting the points to attach and rotate all of the points into my existing cad drawing so that they all come in exactly where they should.

If I know the elevation of the top of foundation from an existing survey I will assign that elevation the existing line work of the building in my cad file so that I can snap that first point to it and it will adjust all of the points to that elevation. This carries the correct topography if you shoot things on the ground such as the edge of a driveway or walk. Some things are shot where their elevation is not the same as the topography such as shooting a tree trunk, but at least the tree location lands where it should in plan view.

The beauty here is that instead of taking a ton of horizontal measurements and notes to go with them and then trying to draft from those notes, you can just import the dxf file, rotate it into place, and look at the photos to confirm what each point represents. If you shoot things in the right order, it will essentially draft the line work for you.

If you don’t want to deal with the vertical values of the points, you have the choice of using any one of the 3 dxf files it makes. One is 3d, one is plan view with x,y coordinates, and another is 2d on a vertical plane. The benefit of the second one is that the lines between the points are accurate in length for plan view (ie, if you locate the top left corner of a building and then the lower right the line will match the length of the building rather than the length of a string connecting the two points.

It is similar to using a survey instrument to locate things except that it is very simple to use without any training.

[Philippa Wilson]

Hi Andrew

I’m considering purchasing the Disto S910 or maybe a total station. So far the Disto seems as if it would be easier to use. I have a couple of questions for you –

Is it easy to position the laser dot accurately outdoors? I have an older laser & have found it really difficult to hold it still & see it in bright sunlight.

Did you get the package with the tripod? I saw somewhere that  the black tripod was difficult to keep steady outdoors???

Thanks

Philippa.

[Andrew Garulay, RLA]

Hi Philippa,

I did get the tripod package. You are correct that the tripod is not great for the outdoors. I got a regular survey tripod and an adapter nut so that the unit can sit firmly and steady. I don’t regret buying the kit because it comes with a good case to carry it safely and you need the piece that sits on top of the tripod which costs more than the additional cost of the kit. I got mine from Amazon for about $1,700..

It is just as hard to see in the bright sun as any laser, but it is steady on the tripod and you have the camera that helps a lot. The camera is not the greatest resolution, but it makes you know where it is pointed. I like visual confirmation as well. I have a couple of pairs of laser glasses (amazon around $15 or so) – they help tremendously to see the red dot (just don’t take notes with a red pen because you won’t see them).

It also comes with a target that you can set on what you want to shoot – I’m usually too impatient for that. I’m almost always by myself, so it works best on things that have some vertical dimension meaning it can be questionable locating the edge of a walkway next to grass if you are not elevated vs. locating a tree for example. I will be considering carrying some things in my trunk to use as targets on the ground – not sure just what, but I’ll come up with something (golf balls, maybe cut pieces of pvc pipe).

The key is the first two points that you locate so that you can tie all the points to some anchor in your drawing. Also to have the camera on so that you get a picture to go with each point in your drawing.

A big difference between this and a total station is that you don’t need a data collector and special software to import the points. You simply plug it into a usb port to drag and drop the folder with the dxf file and photos into your computer then insert the dxf file as a block into the drawing. The first point is the insertion point of the block.

I try to locate the left corner of a building first (anywhere vertically that I have a clear shot), then the right corner second, and the door threshold third (so I can adjust the elevation later) – then shoot everything else.

If you have an existing drawing in AutoCAD that has the building in it you simply import the dxf file exactly like you would a dwg block. Check “specify on screen” for insertion point AND rotation. Simply use the “end point” snap to stick the first point (connected by lines) on the corner of the building and the second will rotate with your mouse to the other corner and you are all lined up. Don’t explode the block, not yet anyway, If you know the first floor elevation of the building (your threshold shot), you can draw a polyline segment (to nowhere) from your third point – use your properties menu to change the elevation of the polyline to match the floor elevation. Move the dxf block using the endpoint of the line in the dxf file at the threshold point and snap it to the endpoint of the polyline segment that matches the floor elevation. Now all your points have the right elevation for your drawing. Far easier than it sounds.

Text next to each point has the referenced photo name that corresponds with the point in AutoCAD Lt or the actual image next to it if you have real AutoCAD – I use Lt.

The real tripod is much easier to get the device level and keep it that way. The adapter that holds the disto has fine tuning knobs to move the laser dot. My only complaint is that the fine tuning knob for turning horizontally does not work if the tripod is attached too tightly and it worries me that it might move if not tight enough.

I do not regret the purchase at all.

[Philippa Wilson]

Thank you so much for your in depth reply. Great to hear how you use the Disto it out in the field.

I was just wondering – are you able to set the elevation to ‘0’ for your first measurement – like you can on a zip level? (For example – make the house floor level ‘0’ & the all the other elevations would relate back to that.)

I use Vectorworks, so I think importing the information from the Disto into the program would be fairly similar to what you do in AutoCAD.

Love the idea of reducing the amount of time it takes to gather the information & create a base plan. Also being able to do it by myself will be a big bonus!

Thanks again for taking the time to answer my questions. Much appreciated!

[Andrew Garulay, RLA]

“I was just wondering – are you able to set the elevation to ‘0’ for your first measurement – like you can on a zip level? (For example – make the house floor level ‘0’ & the all the other elevations would relate back to that.)”

That is exactly what it does. The first point that you shoot will be 0,0,0 (x,y,z coordinates) every time and everything else is in reference to that first point in each dxf file. The entire dxf file will be a block that is all locked together as a unit until you “explode” it.

That makes it really easy for you to adjust all of the elevations to any known elevation of just one point. Usually, a house site plan will have either the top of foundation or first floor elevation written on it assuming that you have an existing plan and you are supplementing information.

If you are starting from scratch just make sure that you are able to reference a consistent elevation for each of your point files. You can only take 30 shots per file. Then you need to start again for the next 30. Often the siding on a building is consistent all the way around a building, so that can be an option. You can always use your ziplevel to mark a reference if you need to.

[andrea valdez]

Nice to got introduced to a new instrument. Thanks.

[Martin Wilder]

Thanks Philippa for all of these usefull information.

I would like to buy the Disto S910 after reading the review http://www.laser-distance-measurer.com/leica-disto-s910-review and your posts. Have you tried the Disto Sketch app for documentation without coordinates? I’m afraid the gadget is expensive…

[Andrew Garulay, RLA]

Martin, I have not used the sketch app. I use the Disto pretty much for one purpose. That is to field locate existing objects or edges to add into and existing plan. It is a lot of money, so it only makes sense if it fits your needs and the frequency of that need. I very often need to supplement a plan with the location of individual existing trees or maybe a walkway or path that the surveyors did not have a need to locate or because I am using an older base plan.

I was already taking these measurements with tapes and laser distance measurers and writing them down and then having to draft them into the plan without the greatest accuracy. It takes time to measure from each object to two or three points on a building or whatever your reference object it. Then you have to measure the reference object to confirm that it matches your drawing. After that you have to draw circles from the reference points for each measurement to locate each tree on the plan. Since I was doing all of that on 15 to 20 jobs a year it makes a lot of sense for me to drop $1,700 on this.

Now I set it up, locate the reference object (usually the corners of a house), aim and shoot at each thing that I want to locate, import the points into my drawing and rotate them into position. I refer to the pictures that go with each point so I know what the point represents. It easily saves me an hour or two every time I use it and the accuracy is much better.

I would not say it increases my capabilities, but it makes tasks that I was already doing far more efficient and accurate.

[Martin Wilder]

Hi Andrew

Thank you very much for the explanation of your typical measuring case. As far as I know there is nothing comparable for this case in price and features as the Leica S910.

I hope I can afford it soon.

[Philippa Wilson]

I have just purchased the Disto S910 & am very pleased with it. I haven’t used it for an actual project yet but have had a play around with it. It seems to be very quick & easy to use. The screen is a little difficult to see in bright sunlight (much like a mobile phone screen in sunlight) but its not too bad. I downloaded the measurements in DXF straight into my Vectorworks  program & it produced a 3D drawing showing all the points I had recorded which are all connected by lines. This was extremely quick & accurate & I can see that this is going to save me heaps of time in preparing accurate base plans. The photographs of each point will be useful to – as a reference when I can’t remember what point I measured! I am in the process of figuring how how to use bluetooth to connect the disto to my laptop so that I can record endless points & see them in Vectorworks on-site, so that if I miss something – I will hopefully notice & rectify it before leaving the site, which will save in travel time & frustration! The only thing I can see that will take a bit of figuring out is that all points you measure are connected by a line & those lines can’t cross over each other, so I guess you need to plan your approach before starting to measure. Overall I am very impressed with its capabilities! (Thanks Andrew for all the information you provided about the Disto – I probably wouldn’t have purchased it without a review from someone using it for the same sort of work.) 

[Andrew Garulay, RLA]

I’m glad it looks like it will work out for you.

I have not had problems with crossing lines. I’m not sure what you are running into with that.

[Kirk Bianchi]

Good morning! In years past, I used an app called Orthograph to draft the house and yard in, and then use the disto 810 I had at the time to collect dimensions and edit the file on the ipad on the fly. When I left the site, I had a dwg file drawn up and ready to start working with.

I no longer have the 810, and am intrigued by the 910 and the 3D dxf point collection it can do. Not sure if that is overkill for what I need?
Looks like if I collect 3D points, I will still have to do the drafting back at my desk to get the as built plan. But maybe that is fast and easy to trace once you have the points to reference?

I’m trying to make sure I don’t get distracted by a cumbersome piece of technology that takes me from my goal of a 2D drafted as built plan as swiftly as possible.

Yes, I’m starting to work in 3D so I should get the 910 I am thinking and grow into it.

Kirk

[Andrew Garulay, RLA]

Kirk,

I most often use it to 2d draft in plan view. It creates three dxf files. One is a 2d plan view using the xy coordinates, one does it 2d elevation (x,z?), and the other is x,y,z. I most often use the plan view dxf to draft the as-built in plan view. If I also need spot elevations, I will add the 3d dxf as long as I have shot something with a known elevation (usually first floor or top of foundation. I’ll draw a short poly line from that point and then change the elevation of the polyline to match the known elevation and then snap that matching point to the end of the polyline which brings all of the points to the proper elevation. Then I can use the “ID” command to query the elevation of any other point and add text to that area to label the spot elevation.

I use ACADlt, so all my drafting is plan view, but it does recognize z coordinate and the dwg is still has x,y,z. You just can’t make 3d solid objects or view your work in any other way than plan view.

It is very quick to set up, shoot, and break down.

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