NDVI computation fails

[m-mohr]

I'm trying to run a very simple max NDVI, but it errors:

Server error: unsupported operand type(s) for *: 'float' and 'NoneType'

Server: https://openeo-dev.sinergise.com/testing
Batch Job ID: 378bba68-b05f-465f-8000-daa67bd525c5

{
  "process_graph": {
    "loadco1": {
      "process_id": "load_collection",
      "arguments": {
        "id": "SENTINEL2_L2A",
        "spatial_extent": {
          "west": 7.6092989782618545,
          "east": 7.623309270052491,
          "south": 51.95464035469027,
          "north": 51.95925713083062
        },
        "temporal_extent": [
          "2017-07-01",
          "2017-08-01"
        ],
        "bands": [
          "B08",
          "B04"
        ]
      },
      "description": "Load the data, including the bands:\r\n- N = B08\r\n- R = B04"
    },
    "reduce1": {
      "process_id": "reduce_dimension",
      "arguments": {
        "data": {
          "from_node": "loadco1"
        },
        "reducer": {
          "process_graph": {
            "max1": {
              "process_id": "max",
              "arguments": {
                "data": {
                  "from_parameter": "data"
                }
              },
              "result": true
            }
          }
        },
        "dimension": "t"
      },
      "description": "Compute the max over the temporal dimension"
    },
    "reduce2": {
      "process_id": "reduce_dimension",
      "arguments": {
        "data": {
          "from_node": "reduce1"
        },
        "reducer": {
          "process_graph": {
            "arraye1": {
              "process_id": "array_element",
              "arguments": {
                "data": {
                  "from_parameter": "data"
                },
                "index": 0
              }
            },
            "arraye2": {
              "process_id": "array_element",
              "arguments": {
                "data": {
                  "from_parameter": "data"
                },
                "index": 1
              }
            },
            "subtra1": {
              "process_id": "subtract",
              "arguments": {
                "x": {
                  "from_node": "arraye1"
                },
                "y": {
                  "from_node": "arraye2"
                }
              }
            },
            "add1": {
              "process_id": "add",
              "arguments": {
                "x": {
                  "from_node": "arraye1"
                },
                "y": {
                  "from_node": "arraye2"
                }
              }
            },
            "divide1": {
              "process_id": "divide",
              "arguments": {
                "x": {
                  "from_node": "subtra1"
                },
                "y": {
                  "from_node": "add1"
                }
              },
              "result": true
            }
          }
        },
        "dimension": "bands"
      },
      "description": "Compute the NDVI (Normalized Difference Vegetation Index) for the bands dimension\r\nFormula: (N - R)/(N + R)"
    },
    "savere1": {
      "process_id": "save_result",
      "arguments": {
        "data": {
          "from_node": "reduce2"
        },
        "format": "GTIFF"
      },
      "description": "Store as GTIFF",
      "result": true
    }
  }
}

[dthiex]

Is there any specific reason why you calculate the NDVI using openEO processes instead of using the NDVI process directly? There is a not so trivial bug with this, but using the NDVI process directly should work.

[m-mohr]

It's just an example. I could have chosen any other spectral indice from the Wizard in the Web Editor.

[dthiex]

Yes, the same bug unfortunately applies to all such indice constructs... Thanks for reporting!