Surface3D makes random lines

[Abanoub Ghadban]

Hi,

I want to to draw 3d surface using some points, I use Surface3D to draw that surface.
The problem is Surface3D always create random lines from beginning and ending of surface to the origin point (0,0,0), however the origin point doesn't exist in my cloud points.

For example, I run this code
main.qml

import QtQuick 2.1
import QtQuick.Controls 2.2
import QtQuick.Layouts 1.0
import QtDataVisualization 1.3

Rectangle {
    id: mainview
    width: 1024
    height: 768
    color: surfacePlot.theme.windowColor

    Data {
        id: surfaceData
    }

    Item {
        id: surfaceView
        width: mainview.width
        height: mainview.height
        anchors.top: mainview.top
        anchors.left: mainview.left

        ColorGradient {
            id: surfaceGradient
            ColorGradientStop { position: 0.0; color: "darkslategray" }
            ColorGradientStop { id: middleGradient; position: 0.25; color: "peru" }
            ColorGradientStop { position: 1.0; color: "red" }
        }

        Surface3D {
            id: surfacePlot
            width: surfaceView.width
            height: surfaceView.height
            //! [7]
            theme: Theme3D {
                type: Theme3D.ThemeStoneMoss
                font.family: "STCaiyun"
                font.pointSize: 35
                colorStyle: Theme3D.ColorStyleRangeGradient
                baseGradients: [surfaceGradient]
            }
            //! [7]
            shadowQuality: AbstractGraph3D.ShadowQualityNone
            selectionMode: AbstractGraph3D.SelectionSlice | AbstractGraph3D.SelectionItemAndRow
            scene.activeCamera.cameraPreset: Camera3D.CameraPresetIsometricLeft
            axisX.min: 0
            axisX.max: 500
            axisY.min: 20
            axisY.max: 300
            axisZ.min: 0
            axisZ.max: 500
            axisX.segmentCount: 10
            axisX.subSegmentCount: 2
            axisX.labelFormat: "%i"
            axisZ.segmentCount: 10
            axisZ.subSegmentCount: 2
            axisZ.labelFormat: "%i"
            axisY.segmentCount: 5
            axisY.subSegmentCount: 2
            axisY.labelFormat: "%i"
            axisY.title: "Height"
            axisX.title: "Latitude"
            axisZ.title: "Longitude"

            //! [5]
            Surface3DSeries {
                id: surfaceSeries
                flatShadingEnabled: false
                drawMode: Surface3DSeries.DrawSurface

                ItemModelSurfaceDataProxy {
                    itemModel: surfaceData.model
                    rowRole: "longitude"
                    columnRole: "latitude"
                    yPosRole: "height"
                }
            }
        }
    }
}

Data.qml

import QtQuick 2.1

Item {
    property alias model: dataModel

    //! [0]
    ListModel {
        id: dataModel
        ListElement{ longitude: 50; latitude: 200; height: 50; }
        ListElement{ longitude: 50; latitude: 210; height: 53; }
        ListElement{ longitude: 50; latitude: 220; height: 50; }
        ListElement{ longitude: 50; latitude: 230; height: 51; }
        ListElement{ longitude: 50; latitude: 240; height: 52; }
        ListElement{ longitude: 50; latitude: 250; height: 54; }
        ListElement{ longitude: 50; latitude: 260; height: 54; }
        ListElement{ longitude: 50; latitude: 270; height: 51; }
        ListElement{ longitude: 50; latitude: 280; height: 51; }
        ListElement{ longitude: 50; latitude: 290; height: 51; }
        ListElement{ longitude: 50; latitude: 300; height: 52; }
        ListElement{ longitude: 50; latitude: 310; height: 50; }
        ListElement{ longitude: 50; latitude: 320; height: 54; }
        ListElement{ longitude: 50; latitude: 330; height: 54; }
        ListElement{ longitude: 50; latitude: 340; height: 50; }
        ListElement{ longitude: 50; latitude: 350; height: 54; }
        ListElement{ longitude: 50; latitude: 360; height: 52; }
        ListElement{ longitude: 50; latitude: 370; height: 50; }
        ListElement{ longitude: 50; latitude: 380; height: 53; }
        ListElement{ longitude: 50; latitude: 390; height: 54; }
        ListElement{ longitude: 60; latitude: 400; height: 50; }
        ListElement{ longitude: 60; latitude: 390; height: 50; }
        ListElement{ longitude: 60; latitude: 380; height: 50; }
        ListElement{ longitude: 60; latitude: 370; height: 51; }
        ListElement{ longitude: 60; latitude: 360; height: 53; }
        ListElement{ longitude: 60; latitude: 350; height: 52; }
        ListElement{ longitude: 60; latitude: 340; height: 51; }
        ListElement{ longitude: 60; latitude: 330; height: 53; }
        ListElement{ longitude: 60; latitude: 320; height: 54; }
        ListElement{ longitude: 60; latitude: 310; height: 51; }
        ListElement{ longitude: 60; latitude: 300; height: 54; }
        ListElement{ longitude: 60; latitude: 290; height: 53; }
        ListElement{ longitude: 60; latitude: 280; height: 53; }
        ListElement{ longitude: 60; latitude: 270; height: 52; }
        ListElement{ longitude: 60; latitude: 260; height: 51; }
        ListElement{ longitude: 60; latitude: 250; height: 54; }
        ListElement{ longitude: 60; latitude: 240; height: 53; }
        ListElement{ longitude: 60; latitude: 230; height: 51; }
        ListElement{ longitude: 60; latitude: 220; height: 51; }
        ListElement{ longitude: 60; latitude: 210; height: 54; }
        ListElement{ longitude: 60; latitude: 200; height: 54; }
        ListElement{ longitude: 60; latitude: 190; height: 50; }
        ListElement{ longitude: 60; latitude: 180; height: 54; }
        ListElement{ longitude: 60; latitude: 170; height: 50; }
        ListElement{ longitude: 60; latitude: 160; height: 54; }
        ListElement{ longitude: 60; latitude: 150; height: 53; }
        ListElement{ longitude: 60; latitude: 140; height: 54; }
        ListElement{ longitude: 60; latitude: 130; height: 50; }
        ListElement{ longitude: 60; latitude: 120; height: 52; }
        ListElement{ longitude: 60; latitude: 110; height: 50; }
        ListElement{ longitude: 60; latitude: 100; height: 52; }
        ListElement{ longitude: 60; latitude: 90; height: 50; }
        ListElement{ longitude: 60; latitude: 80; height: 50; }
        ListElement{ longitude: 60; latitude: 70; height: 51; }
        ListElement{ longitude: 60; latitude: 60; height: 54; }
        ListElement{ longitude: 60; latitude: 50; height: 52; }
        ListElement{ longitude: 60; latitude: 40; height: 53; }
        ListElement{ longitude: 60; latitude: 30; height: 54; }
        ListElement{ longitude: 60; latitude: 20; height: 50; }
        ListElement{ longitude: 60; latitude: 10; height: 50; }
        ListElement{ longitude: 70; latitude: 0; height: 51; }
        ListElement{ longitude: 70; latitude: 10; height: 52; }
        ListElement{ longitude: 70; latitude: 20; height: 54; }
        ListElement{ longitude: 70; latitude: 30; height: 52; }
        ListElement{ longitude: 70; latitude: 40; height: 54; }
        ListElement{ longitude: 70; latitude: 50; height: 51; }
        ListElement{ longitude: 70; latitude: 60; height: 53; }
        ListElement{ longitude: 70; latitude: 70; height: 50; }
        ListElement{ longitude: 70; latitude: 80; height: 53; }
        ListElement{ longitude: 70; latitude: 90; height: 54; }
        ListElement{ longitude: 70; latitude: 100; height: 54; }
        ListElement{ longitude: 70; latitude: 110; height: 54; }
        ListElement{ longitude: 70; latitude: 120; height: 53; }
        ListElement{ longitude: 70; latitude: 130; height: 53; }
        ListElement{ longitude: 70; latitude: 140; height: 52; }
        ListElement{ longitude: 70; latitude: 150; height: 52; }
        ListElement{ longitude: 70; latitude: 160; height: 53; }
        ListElement{ longitude: 70; latitude: 170; height: 52; }
        ListElement{ longitude: 70; latitude: 180; height: 50; }
        ListElement{ longitude: 70; latitude: 190; height: 51; }
        ListElement{ longitude: 70; latitude: 200; height: 53; }
        ListElement{ longitude: 70; latitude: 210; height: 54; }
        ListElement{ longitude: 70; latitude: 220; height: 50; }
        ListElement{ longitude: 70; latitude: 230; height: 51; }
        ListElement{ longitude: 70; latitude: 240; height: 50; }
        ListElement{ longitude: 70; latitude: 250; height: 54; }
        ListElement{ longitude: 70; latitude: 260; height: 50; }
        ListElement{ longitude: 70; latitude: 270; height: 50; }
        ListElement{ longitude: 70; latitude: 280; height: 51; }
        ListElement{ longitude: 70; latitude: 290; height: 53; }
        ListElement{ longitude: 70; latitude: 300; height: 50; }
        ListElement{ longitude: 70; latitude: 310; height: 53; }
        ListElement{ longitude: 70; latitude: 320; height: 52; }
        ListElement{ longitude: 70; latitude: 330; height: 51; }
        ListElement{ longitude: 70; latitude: 340; height: 53; }
        ListElement{ longitude: 70; latitude: 350; height: 51; }
        ListElement{ longitude: 70; latitude: 360; height: 52; }
        ListElement{ longitude: 70; latitude: 370; height: 51; }
        ListElement{ longitude: 70; latitude: 380; height: 53; }
        ListElement{ longitude: 70; latitude: 390; height: 54; }
        ListElement{ longitude: 80; latitude: 400; height: 54; }
        ListElement{ longitude: 80; latitude: 390; height: 52; }
        ListElement{ longitude: 80; latitude: 380; height: 53; }
        ListElement{ longitude: 80; latitude: 370; height: 51; }
        ListElement{ longitude: 80; latitude: 360; height: 50; }
        ListElement{ longitude: 80; latitude: 350; height: 52; }
        ListElement{ longitude: 80; latitude: 340; height: 53; }
        ListElement{ longitude: 80; latitude: 330; height: 52; }
        ListElement{ longitude: 80; latitude: 320; height: 51; }
        ListElement{ longitude: 80; latitude: 310; height: 53; }
        ListElement{ longitude: 80; latitude: 300; height: 54; }
        ListElement{ longitude: 80; latitude: 290; height: 53; }
        ListElement{ longitude: 80; latitude: 280; height: 52; }
        ListElement{ longitude: 80; latitude: 270; height: 54; }
        ListElement{ longitude: 80; latitude: 260; height: 53; }
        ListElement{ longitude: 80; latitude: 250; height: 50; }
        ListElement{ longitude: 80; latitude: 240; height: 54; }
        ListElement{ longitude: 80; latitude: 230; height: 50; }
        ListElement{ longitude: 80; latitude: 220; height: 50; }
        ListElement{ longitude: 80; latitude: 210; height: 52; }
        ListElement{ longitude: 80; latitude: 200; height: 50; }
        ListElement{ longitude: 80; latitude: 190; height: 50; }
        ListElement{ longitude: 80; latitude: 180; height: 50; }
        ListElement{ longitude: 80; latitude: 170; height: 51; }
        ListElement{ longitude: 80; latitude: 160; height: 52; }
        ListElement{ longitude: 80; latitude: 150; height: 53; }
        ListElement{ longitude: 80; latitude: 140; height: 50; }
        ListElement{ longitude: 80; latitude: 130; height: 51; }
        ListElement{ longitude: 80; latitude: 120; height: 50; }
        ListElement{ longitude: 80; latitude: 110; height: 52; }
        ListElement{ longitude: 80; latitude: 100; height: 53; }
        ListElement{ longitude: 80; latitude: 90; height: 54; }
        ListElement{ longitude: 80; latitude: 80; height: 53; }
        ListElement{ longitude: 80; latitude: 70; height: 50; }
        ListElement{ longitude: 80; latitude: 60; height: 54; }
        ListElement{ longitude: 80; latitude: 50; height: 53; }
        ListElement{ longitude: 80; latitude: 40; height: 52; }
        ListElement{ longitude: 80; latitude: 30; height: 50; }
        ListElement{ longitude: 80; latitude: 20; height: 54; }
        ListElement{ longitude: 80; latitude: 10; height: 50; }
        ListElement{ longitude: 90; latitude: 0; height: 53; }
        ListElement{ longitude: 90; latitude: 10; height: 52; }
        ListElement{ longitude: 90; latitude: 20; height: 52; }
        ListElement{ longitude: 90; latitude: 30; height: 53; }
        ListElement{ longitude: 90; latitude: 40; height: 54; }
        ListElement{ longitude: 90; latitude: 50; height: 52; }
        ListElement{ longitude: 90; latitude: 60; height: 52; }
        ListElement{ longitude: 90; latitude: 70; height: 54; }
        ListElement{ longitude: 90; latitude: 80; height: 50; }
    }
}

I suppose that a thin surface should be rendered, but the following surface is rendered

Can anyone explain why there are lines between edges of surface and origin point and how can I eliminate them ?

Thanks!