[GRASS-dev] NVIZ problem with 3D polygons

[Markus Neteler]

On Thu, Aug 11, 2011 at 11:30 AM, del cadarn <del_cadarn at hotmail.com> wrote:

>  Bonjour,
>
> I've also posted this on the GRASS-users mailist but since I didn't receive
> an answer, I thought I might try this one.
>

Sorry, I overlooked it.


> I am having problems to see vectors I have added height to with v.extrude .
> The trick is that I am actually using the e.g. given in NETELER, M and H.
> MITASOVA *Open Source GIS a GRASS GIS Approach* with the North Carolina
> sample data. So in theory, this example should really be working...
>

Thanks :) But there was an error in that part of the book:

http://www.grassbook.org/errata_menu3rd.php



> Here is what I did
>
> g.region rast=el_D792_6m -p
>
> v.extract P079215 out=bldg_resid_a where="layer='BLDG_RESID_BL'"
> v.extract P079215 out=bldg_cmcl_a where="layer='BLDG_COMMER_BL'"
>

Here the step to change the vector type was omitted in the book example.

v.info bldg_resid_a -t
nodes=14
points=0
lines=11
boundaries=0
centroids=0
areas=0
islands=0
faces=0
kernels=0
primitives=11
map3d=1

--> no boundaries but lines only.

So you need to perform here:

v.type bldg_resid_a out=bldg_resid_bnd type=line,boundary
v.centroids bldg_resid_bnd out=bldg_resid_pol
v.type bldg_cmcl_a out=bldg_cmcl_bnd type=line,boundary
v.centroids bldg_cmcl_bnd out=bldg_cmcl_pol

# add height of the building (use new input maps)
v.extrude -t bldg_resid_pol out=bldg_resid_a_3d height=10 \
    elev=el_D792_6m
v.extrude -t bldg_cmcl_pol out=bldg_cmcl_a_3d height=15 \
    elev=el_D792_6m

# verify
v.info -t bldg_resid_a_3d | grep faces
faces=36

v.info -t bldg_cmcl_a_3d | grep faces
faces=55


g.region rural_1m -p
nviz elev_lid792_1m col=ortho_2001_t792_1m
vect=bldg_resid_a_3d,bldg_cmcl_a_3dI've encountered also this problem when I
tried to visualised a DXF file in NVIZ. The windmill shows up but in broken
lines which is no good to me.

... now you see the buildings nicely.

> Thank you for your help, I'm very new to GIS and Open Source, and I must
admit I don't know where to find the ressources to help...


It will be the same problem with solution to be applied from above.

Hope this helps,
Markus

-- 
http://www.grassbook.org/neteler/
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