Hi All,
I am using pgr_nodeNetwork with threshold 0.00001 to create nodes and pgr_createTopology with a threshold of 0.0001 on the GPS traces which I have collected. The resultant graph from this data looks weird due to the creation of nodes so close to each other as I have visualized in the attached pictures. The black circles are the nodes and you could see that they are created such a way they are overlapping densely. I thought using pgr_nodeNetwork threshold could solve this issue but it did not help me in this case.
If I increase the threshold above 0.00001, I get the following error
psql:run_pgr_node_network.sql:1: ERROR: getPoint4d_p: point offset out of range
CONTEXT: SQL statement “create temp table inter_loc on commit drop as ( select * from (
(select l1id, l2id, st_linelocatepoint(line,source) as locus from intergeom)
union
(select l1id, l2id, st_linelocatepoint(line,target) as locus from intergeom)) as foo
where locus<>0 and locus<>1)”
PL/pgSQL function pgr_nodenetwork(text,double precision,text,text,text) line 184 at EXECUTE statement
So the graph formed out of my GPS traces is so noisy and not able to use it for any of my experiments. Please suggest if I can use any other function or approach to make my graph with more cleaner structure.
–
Thanks,
Raghavan KL
Hi Raghavan,
pgr_nodeNetwork is not intended for this purpose. It assumes you have a series of street segments that might not be noded correctly and then chops them into smaller segments that are noded where they cross one another.
We do not have tools for building well structured street networks from multiple GPS tracks. You have to convert the tracks to streets before coming to pgRouting. Look at postGIS or OSM as they have tools that are more appropriate to this task.
Thanks,
-Steve
On 4/21/2014 3:51 PM, Raghavan Krishnasamylakshmanaperumal wrote:
Hi All,
I am using pgr_nodeNetwork with threshold 0.00001 to create nodes and
pgr_createTopology with a threshold of 0.0001 on the GPS traces which I
have collected. The resultant graph from this data looks weird due to
the creation of nodes so close to each other as I have visualized in the
attached pictures. The black circles are the nodes and you could see
that they are created such a way they are overlapping densely. I thought
using pgr_nodeNetwork threshold could solve this issue but it did not
help me in this case.
If I increase the threshold above 0.00001, I get the following error
psql:run_pgr_node_network.sql:1: ERROR: getPoint4d_p: point offset
out of range
CONTEXT: SQL statement "create temp table inter_loc on commit drop
as ( select * from (
(select l1id, l2id, st_linelocatepoint(line,source) as
locus from intergeom)
union
(select l1id, l2id, st_linelocatepoint(line,target) as
locus from intergeom)) as foo
where locus<>0 and locus<>1)"
PL/pgSQL function pgr_nodenetwork(text,double
precision,text,text,text) line 184 at EXECUTE statement
So the graph formed out of my GPS traces is so noisy and not able to use
it for any of my experiments. Please suggest if I can use any other
function or approach to make my graph with more cleaner structure.
--
Thanks,
Raghavan KL
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