TopoToolbox Short Course at the IIT Roorkee

Today, Oct 18 2023, Jürgen Mey and I will give a short course on TopoToolbox at the IIT Roorkee/India. The course follows a field trip with students to the Indian Himalayas within the project Co-PREPARE funded by the University Grant Commission (UGC) and German Academic Exchange Service (DAAD) through the Indo German Partnership in Higher Education (IGP 2020-2024).

In this course, we will offer an introduction to analyzing point patterns on river networks, thus linking digital terrain analysis with spatial statistics. The example, which we’ll use, will be about landslides along the NH-7, an important road linking Rishikesh and Joshimath. The example script and all the data can be downloaded (PW: IIT_Roorkee_course). The code used to offer a brief insight into TopoToolbox is shown below.

%% GRIDobj
DEM = GRIDobj('srtm_bigtujunga30m_utm11.tif');

% show DEM
figure
subplot(2,2,1)
imagesc(DEM)
subplot(2,2,2)
imageschs(DEM)
subplot(2,2,3)
surf(DEM)
camlight
material dull

% Calculate slope
G = arcslope(DEM);

figure
surf(DEM,G); camlight; caxis([0 1]); colormap(flipud(magmacolor));

%% FLOWobj
FD = FLOWobj(DEM);
A = flowacc(FD);
figure
subplot(1,2,1)
imagesc(A); colormap(flowcolor)

methods FLOWobj
D = drainagebasins(FD);

subplot(1,2,2)
imagesc(D)

%% STREAMobj
S = STREAMobj(FD,'minarea',1000);
figure
subplot(1,2,1)
plot(S,'color','r','linewidth',2)
S = klargestconncomps(S,1);
hold on
plot(S,'color','r','linewidth',2)
subplot(1,2,2)
plotdz(S,DEM)

%% PPS
% complete spatial randomness
P = PPS(S,'rpois',0.0001,'z',DEM);
figure
subplot(1,2,1)
plot(P)
P = PPS(S,'rpois',0.0001,'z',DEM);

subplot(1,2,1)
P = PPS(S,'rpois',0.0005,'z',DEM);
plot(P)

cdftest(P)

% Inhomogeneous Poisson process
P = simulate(P,'intensity',getnal(S,DEM)/1e6);
cdftest(P)
figure
subplot(2,2,1)
plotdz(P)
subplot(2,2,2)
rhohat(P,'cov',DEM)
[mdl,int] = fitloglinear(P,DEM);
subplot(2,2,4)
ploteffects(P,mdl)