Site massing coodinate system

[RudyBeuc]

I have been wresteling with this problem for some time. I do alot of smaller projects. Most of the time a survey with countours does not exist. So I go out to the site with a laser level, take grades, and create a site model with that information using the first floor level as base datum 100 feet or sometimes 0.

Then later on mabey I'll find a good benchmark and then have to adjust everything to the new elevation data. Pinning, unpinning the project basepoint, moving everything up and down and so forth. It's a real hassel and I have yet to figure out the real reason why some thing are acting the way they do. It's alot of trial and error, and when it gets right, I don't know how I got there.

Please see the attached project file. It's from Revit 2017 but I've experienced the same problems from 2014 on. Go to edit the sites and observe the elevations of the points used to create the sites. They seem to have no relation to the survey point or project base point.

What's up? The only narritave that makes sence to me is that there is an invisiable set of coordinates that got thrown off with all of my manuvering.

Thanks,

Rudy Beuc

[Mirko.Jurcevic]

Hi Rudy!

Unfortunately, you are right. Topography doesn't have any relation to the survey or project base point (at least I was not be able to find one).

What's going on is next: when you create the topography, it's "zero" is at project base point (relative project zero).

But, if you change your Project Base Point (PBP), (you change project relative zero), your topo will stay where it is.

Then, you move it, for example 100m up to stay right where it should be in reality, when you edit it, points of the topography will still have "0" and all of the original point elevation values.

What I usually do is to create topography based on the AutoCAD dwg lines or points on the "correct" altitudes.

Hope it helps!

[loboarch]

This video might help. it shows how to set up a project to place toposurface elevation points using sea level elevations.

http://help.autodesk.com/view/RVT/2017/ENU/?guid=GUID-B73E0D49-3330-4876-B8BD-7C23B9340626

[RudyBeuc]

Ok, so by that reasoning, if I create a new site massing with points at absolute elevation 0, then the sithe should be in line with the project base point.

Please see the attached file "Project1-A". It did not seem to work out that way.

Thanks,

Rudy Beuc

[RudyBeuc]

Ok, have never used the relocate project tool to change elevtions. Have been moveing the project and survey base points.

Why isn't just moving the survey point have the same effect?

Thanks,

Rudy Beuc

[Mirko.Jurcevic]

Hi, I wrote from head so I probably wrote it wrong.

Here, http://screencast.com/t/cfdPFj0sgar7

I recorded a short video to show you what I was trying to say.

As you can se, movin WILL change topo points height, but changing the UNCLIPPED Project Base Point and/or Survery point will not change the topo points heights.

[RDAOU]

@RudyBeuc

Moving the Survey Point CLIPPED has the same effect...it would mean basically; indirectly relocating/moving your whole project (including the Revit Plate ie: Start-up Origin together with the Project Base Point) to a point E:??/N:?? from the origin of the WCS 0,0,0. When it is clipped it means it is clipped to the World Coordinates system. and at start-up (new project template) both WCS and Revit Coordinates System are at 0,0,0

(The benchmark/Survey Point) At this instance - after relocating it clipped

1. if you select the survey point (which is actually the pin/benchmark) it will read E:0 N:0 ELV:0 (a ridiculous benchmark for the site)
2. to relocate it to a place more relevant to the project (example: a corner of the plot) you un-clip it from the WCS and place it at the corner of the plot then clip it again

That point identifies where your site is with respect to the E0,N0

What you need to watch out for is the project base point ... moving it un-clipped is what causes the mess. And for that reason; using a master file for the site separate from that of the building especially when you have more than 1 building on the plot. ie: you use shared coordinates ...which comes best into play when you start modeling your project before you receive any survey data.

1. each model will have its own project base point set at some corner of the building and clipped not to worry about for the rest of the project lifecycle
2. all models have 1 common Benchmark (what is referred to as survey point in Revit) which is shared when you publish to the linked files

Project Base Point

When the Project base point is clipped it means that it is clipped to the Revit Plate where you are modeling and start-up origin. When you un-clip it and move it around it implies moving it away from the start-up origin. On small projects this has less significance BUT on large scale projects where the site and/or the elements/buildings on it exceeds 9.9 miles radius/distance between their extent; there is a chance that the project (entirely of partially) falls outside the 20 miles radius from the start-up origin (that's when Revit will prompt you)

Un-clipping the base point and moving it is more like telling the builder - instead of measuring from the Finish floor level, measure from 1m above finish floor level...or instead from this corner of the building, from the other/opposite corner. I personally never found a reason to move it un-clipped further than those extents (1-20m from where it originally was - the start-up origin) and that is another reason why not to un-clip it through out the whole project till you are set to fine tune the spot coordinates placed in the project.

Changing the elevation

This is the least critical...it can be as easy as

1. entering the value in the Project Base Point while it is clipped (to move the whole project X meters up or Y meters down)
2. and entering the same value in the Survey point UNCLIPPED in order not to move the WCS origin...then clip it again

Some leave the Survey point as is for some odd reason; but I find that ridiculous. Project at 2000 m from sea level and benchmark at sea level!!!... elevation has to go in both otherwise the benchmark doesn't make sense

The other way to this is

1. Either using Relocate project
2. OR setting coordinates at a specific point then moving Project Base Point (CLIPPED) to that point

The only way to understand this is to really understand the 2 coordinates systems .. That of Revit/Project and the WCS (ie: on the 3D view that would be respectively the Cube which resembles the project & project north and the circular compass which resembles the WCS & True North)

Sorry I cannot open your file I don't have 2017

[RudyBeuc]

Thanks everyone for thier posts. The discussion was good.

Right now, so far as I can figures, the points used to create the site massing are using the hidden internal set of coordinates; not the project base point or survey base point grids.

I think unclipping the project base point and moving thing around like I did in earlier projects caused the project base p[oint to be disconnected form the hidden internal set of coordinates, or wcs as  RDAOU calls it. Understanding this is important because I have to fix my project template file.

I think I've figured this out, please see the attached file.

Thanks agian,

Rudy Beuc

[RudyBeuc]

Hey all ...

continued digging and found a great AU course...

http://au.autodesk.com/au-online/classes-on-demand/class-catalog/2013/revit-for-architects/ab1412#ch...

Still think the points used for generating a site massing are tied to the invisable "double secrete" WCS.

Thanks,

Rudy Beuc

[RDAOU]

There is no double WCS and no secret ones.
- There is only 1 WCS for this world and it is fixed and it's origin is at 0,0,0 - you only see it when the Survey point is still at its default location as per template
- then there is another variable coordinate system in Revit which is bound to the center of the Revit plate and it's only visible if the project base point has not been moved unclipped.

Once a user starts messing with clipping and unclipping everything; the user gets confused what went where and where it actually was.

- There are 3 types of spot coordinates annotations (SC)
1. To Base Point (this SC the builder use and it reads coord with respect to the Project Base Point)
2. To Survey Point (this SC surveyors use and it reads its coordinates from/to the WCS 0,0,0 and they are used as benchmarks)
3. Relative (this SC reads its coordinates relative to the Startup Origin and using it one can verify if the Project base point has been displaced)

What I think you are confused about is that reading of the spot coordinates you are using and the relevant point of origin...on top of that you might have moved your project base point and survey point multiple times when it was not clipped which added to the confusion.

[loboarch]

There is an "origin" internal to Revit and it is not marked in any way. By default the Project Base Point starts at this position, but if moved un-clipped, the Project Basepont become separated from the "origin". You can set it back, by un-clipping the Project Basepoint and right clicking and select "Move to Startup Location".

[RDAOU]

@loboarch

---

@loboarch wrote:
There is an "origin" internal to Revit and it is not marked in any way. By default the Project Base Point starts at this position, but if moved un-clipped, the Project Basepont become separated from the "origin". You can set it back, by un-clipping the Project Basepoint and right clicking and select "Move to Startup Location".

---

There is an origin and ONE (ie: the user) can mark it because as long as the Project base point is clipped that origin moves along with the Project base point.

1. When you move the project base point clipped => it moves the whole Revit plate with it INCLUDING PLATE ORIGIN

Use Relative spot coordinate and check it...I will record a screencast and upload it on from my side too

Difference with between relocating the project using Project base point and using the tool Relocate Project is that the latter ignores the status of the clip and moves the plate along anyways

EDIT: SCREENCAST - TRACKING REVIT PLATE / INTERNAL ORIGIN

[RudyBeuc]

Perhaps I haven't been too clear.

I think we're in agreement more than it seams.

Figuring this out has been a long term process. About two years. Over that time I've been updating my inhouse project template file, and apparently have introduced a mistake. I believe that when wrestling with the elevation of points making up a site massing; that is clipping , unclipping the project base point, and moving things around; caused the project base point to become disconnected from the internal WCS of the file. This problem got embedded in my project template file and has existed in every project since then.

Please see the attaches screenshot. The elevation of the point used to create the site has no relationship to the project base point or survey point. I believe the 0 refrences the files internal and hidden coordinate system (or what we are now refreing to as the WCS).

My confusion in the past was not realizing there was a hidden internal coordinate system. I thought the survey point represented one system and the project base point represented another. Then in the process of working with sites, I found thses points sitting on an elevation of 0, but 0 in relation to what?

Figuring this out shoulldn't have been this hard. From here on out I will be graphically marking that 0,0,0, refrence point (WCS) in my flies. What'll be the most appropriate way of doing that I have yet to figure out. Perhaps a set of pinned work planes.

Thanks,

Rudy Beuc

[RDAOU]

@RudyBeuc

Best Practice is to mark both
1. the WCS 0,0,0 (ie: at sea level)
2. the Center of the Revit plate (ie: start up point) --- As shown in the above screentcast

Then you should be able to track both systems (WCS and RCS) as you progress ... When you see the center of the plate markup didn't move along with the Project Base Point ... you will know that you did something wrong ie: you moved PBP unclipped