Hi all,
I would like to request an advice for my school project. I searched through online in several times but couldn’t find the right answer yet. Anyone knows can convert tiff format scan data as a revit mash or form or element. Anyone can advice? Many Thanks 
I would personally recommend trying to process it in Rhino/Grasshopper given it’s such a large scale.
You could try to read the pixels in Dynamo but would need to know the heights that each colour correlates to as well as the sample spacing vs scale it represents to size the outcome points.
Search for scan to mesh in the forums for various approaches that might work once you have points at heights to work with.
You can read GEOTIFF data fairly easily, as the standard is open and available, but why do so when tools which have accounted for all the intricacies are already there?
Utilize your educational license (all the toolsk are available) and leverage native Civil 3D which has tools for this already. No hunting for a solution besides the half dozen steps to import a geotiff. From there you can import the topography into Revit and be done with it.
If you do go into utilizing the geotiff data, I’d memory serves the content is stored in arc degrees of lat/long, and as such the distance in X direction will be inconsistent depending on where in the world the data is from as a degree of longitude will vary by distance from the equator (I think 60km at the equator, 0 at the poles as they all converge) and so things scale in odd ways as you move north). Some tools assume a consistent distance for any location and as a result I have seen real world projects have survey data well out of alignment as a result of not taking this into account. There are also Python libraries which can be used for this, but again don’t just read the elevations and map to a consistent distance. This links looks pretty good for a primer in the concepts involved: Elevation GeoTIFF Part 1 – Shaded Relief
