Comparison of Topographies
you can put both in same file, then assign a different phase for each of them. For example, Topo 1 created in phase 1 and demolished in phase 2. Topo 2 created in phase 2.
in that case, each will have a color. you can compare visually either in 3D or in sections.
In addition, if you select Topo 2, you can find the difference of Cut and Fill between both.
Mostafa Elashmawy
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Yes sure you should first place them per the correct coordinates and levels then apply the phasing to be able to compare them.
It would also help if they exactly have the same boundary.
Mostafa Elashmawy
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Did you read my response?
I didn't say that he should place the two topos to exact same elevation.
I said: " place them per the correct coordinates and levels" "It would also help if they exactly have the same boundary."
If he placed the two Topos in the same file and each Topo have its correct coordinates and level, he can easily compare them.
Usually this practice is done to compare same plot before and after excavation.
Mostafa Elashmawy
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You could have used "Grade Region" tool and generated both topographies in the same file …
If you have them in different files, do the following
1. In File A … export the topo surface to CAD/DWG then close the file
2. Open file B and import CAD
3. Create Toposurface from Import (can delete the imported DWG after)
4. Select 1st toposurface and set Phases
a Created: New Construction
b. Demolished: None
5. Select 2nd toposurface and set Phases
a Created: New Construction
b. Demolished: New Construction
Create schedule to compare cut/fill/net cut and fill/projected area
Ok let me explain more:
Why would we compare two Topos?
Through different projects I worked at, we never compare Topographies unless they are for the same area. For example, we have the existing Topography of some area, then we have another Topography for the same area after expected grading.
We do this to assess the quantity of cut and fill and try to balance them.
for example, we have a small hill in our land and some road need to pass by this hill. if we made our design based on the road passing at the middle of the hill, all the earthwork will be excavation. but if we shifted it a bit to the right, we may have the fill nearly equal the cut so we don't need to pay money for transferring materials or for buying fill material.
In above case, we have three topographies:
1- existing Topo based on points received from site. Coordinates and levels in a grid.
2- First option grading from designer which is points at edges of roads and landscape areas also with coordinates and levels.
3- Second option grading from designer but may be this time as contours from Civil 3D program.
To compare them, we place each topo based on the coordinates and levels. The three Topos will lay at same boundry but each one will have its own points.
I hope that above explains my point of view.
Mostafa Elashmawy
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Another case where I had to compare Topos of same area is when I had 4 Existing Topos from 4 different sources for the plot. The area was huge and no time to send a surveyor to make a detailed survey. We could only take a point every 300m x 300m
1- first Topo was extracted from an DEM - 30 (Digital Elevation Model) from municipality
2- Second Topo was from another model owned by another engineering office
3- Third topo was extracted from Google earth.
4- Fourth Topo is based on the available data from site.
We had to compare each of the 3 Topos to check which of them is the nearest to the fourth Topo from site. by cross checking the elevation at the 300x300 points.
Let me know if that was clear.
Mostafa Elashmawy
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The Graded region way would work if the two topographies have the exact same boundaries.
Mostafa Elashmawy
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