A Topological Framework for Interactive Queries on 3D Models in the Web

Algorithm 4

Contour lines algorithm.

Data: 𝐺=(𝑉,𝐸), 𝑧₀ elevation

Result: 𝐶 set of segments defining 𝐶_𝑧0

𝐶← empty list;

for 𝑒∈𝐸(𝐺)  do

 if 𝑒 intersects 𝐶_𝑧0 then

  𝑇₁,𝑇₂ ← triangles incident on 𝑒

  𝑆_𝑖←𝑇_𝑖∩𝐶_𝑧0, 𝑖=1,2

  append 𝑆_𝑖 to 𝐶

 end

end