Calculate routes via GET - Polyline incorrect

Question

Iam testing routing API(https://developer.here.com/documentation/routing-api/api-reference-swagger.html) and all seems to be working as expect except polyline.

Here I share my service invocation curl --location --request GET 'https://router.hereapi.com/v8/routes?transportMode=car&origin=3.4844257,-76.5256287&destination=3.478483,-76.517984&routingMode=fast&return=elevation,polyline,actions,instructions,summary&apiKey=1234'

As part of response we have the next field:

"polyline": "B2Fkt10Grm4-xE8yTU4mBnBnG8pBAzP0tBAjD4IA_E8LAvMokBT3IkXTzF8QTnG8QTvMsiBTrJjDA3_BjXoB_sB_OAriB3NAzKjDAnLsTAnLkhBnBzKsdA_J8fTnLkcT3DwHAvC8GArJoQAnL8QA7LsTA7V0jBT_M8UA",

As you know the polyline field is encoded. According to documentation I proceeded to decoded it with a library/code suggested from:

https://github.com/heremaps/flexible-polyline/tree/master/java

The result of decode the field in not correct. The list of points (Lat,Long,Elevation) returned are not matched with the correct location. In the example, the coordinates are from Colombia and the results, after decodification, returns a list of points in a middle of the Atlanthic ocean.

Further, in order to discard library issues I was checking decoding de polyline with other decoder as:

And the result is the same.

So, seems to be the problems is HereAPI side(API routing v8)

Any ideas? Maybe I am invoking the API in the incorrect way

score 0 · Answer 1 · answered Feb 17 '22 at 22:37

I would suggest removing your API key from the get request you posted in your question.

Using the polyline that you provided gets decoded into the following, which is in Columbia. As a result, I think you need to check the decoder you are using and/or what is being fed into it.

Index	Lat	Lon	Elev
0	3.48437	-76.52567	1003
1	3.48438	-76.52505	1001
2	3.48428	-76.52438	1001
3	3.48403	-76.52365	1001
4	3.48398	-76.52351	1001
5	3.4839	-76.52332	1001
6	3.4837	-76.52274	1000
7	3.48356	-76.52237	999
8	3.48347	-76.5221	998
9	3.48337	-76.52183	997
10	3.48317	-76.52128	996
11	3.48302	-76.52133	996
12	3.482	-76.5217	998
13	3.48128	-76.52194	998
14	3.48073	-76.52216	998
15	3.48056	-76.52221	998
16	3.48038	-76.5219	998
17	3.4802	-76.52137	996
18	3.48003	-76.5209	996
19	3.47987	-76.52039	995
20	3.47969	-76.51994	994
21	3.47963	-76.51982	994
22	3.47959	-76.51971	994
23	3.47944	-76.51945	994
24	3.47926	-76.51918	994
25	3.47907	-76.51887	994
26	3.47872	-76.5183	993
27	3.478512	-76.517966	993

score 0 · Accepted Answer · answered Feb 22 '22 at 13:56

The decoder on https://github.com/heremaps/flexible-polyline/tree/master/java works correct, see please code with your encoded string:

private void testSOLatLngDecoding() {
        List<LatLngZ> computed = decode("B2Fkt10Grm4-xE8yTU4mBnBnG8pBAzP0tBAjD4IA_E8LAvMokBT3IkXTzF8QTnG8QTvMsiBTrJjDA3_BjXoB_sB_OAriB3NAzKjDAnLsTAnLkhBnBzKsdA_J8fTnLkcT3DwHAvC8GArJoQAnL8QA7LsTA7V0jBT_M8UA");
        List<String> seqCrds = new ArrayList<>();
        for (int i = 0; i < computed.size(); ++i) {
            LatLngZ c = computed.get(i);
            List<String> crds = new ArrayList<>();
            crds.add(String.valueOf(c.lat));
            crds.add(String.valueOf(c.lng));
            crds.add(String.valueOf(c.z));
            seqCrds.add(String.join(",", crds));
            //assertEquals(computed.get(i), pairs.get(i));
        }
        System.out.println(String.join(",", seqCrds));
    }

We have a javascript tool "Encode/Decode to/from Flexible polyline" on https://demo.support.here.com/examples/v3.1/enc_dec_flexible_polyline

see please result:

Please double check code on your side.

Calculate routes via GET - Polyline incorrect

2 Answers2