There are a lot of tools that facilitate this in Mathematica. For rendering terrain ListPlot3D is a very direct solution. You could outgrow it if you wanted terrain involving overhangs etc, but it is a great starting point.

The interesting problems remain generating interesting height data and textures. Here's a quick example!

rawData = RandomReal[{0, 2.5}, {10, 10}];
deltaAdjust[data_] := Sign[data] Abs[data^(1/2)]
dimension1 = Accumulate[deltaAdjust[Prepend[Differences[rawData], rawData[[1]]]]];
dimension2 = Accumulate[deltaAdjust[Prepend[Differences[Transpose[rawData]], 
     Transpose[rawData][[1]]]]];
interestingData = dimension1 + dimension2;
TableForm[{{ListPlot3D[interestingData, InterpolationOrder -> 1, 
    ColorFunction -> Function[{x, y, z}, 
      RGBColor[{0, 0.35, 0} (1 - z) + {1, 1, 1} (z)]], Mesh -> Full],
   ListPlot3D[interestingData, InterpolationOrder -> 2, 
    ColorFunction -> Function[{x, y, z}, 
      RGBColor[{0, 0.35, 0} (1 - z) + {1, 1, 1} (z)]], Mesh -> All]}}]

This is what I've made:

tri[lista_] := Module[{news},
  news = Table[lista[[i]] + lista[[i + 1]], {i, 1, 3}]/2;
  news = Append[news, First[news]];
  news]
   dib= Map[Line, 
      NestList[tri, {{0, 0, 0}, {25, 25 Sqrt[3], 0}, {50, 0, 10}, {0, 0, 
         0}}, 2]];

As you will see in the chart below, it is where I have problems

Graphics3D[dib, Boxed -> False]

I still don't know how to make Mathematica draw triangles as shown in the image below

Could you help me someone please get this image?, I thank you in advance

Thank you for the information but i'm confused about which is the algorithm to use, you could share any to me, in order to work for their implementation or comment on how the strategy is to use, I am curious whether it is true that could not be done in BASIC because I have read little of that language, I hope I can help her to understand how to do this in Mathematica