topic Re: Qml - load a tif map and use it offline, without any online base map? in Qt Maps SDK Questions

Qml - load a tif map and use it offline, without any online base map?

AnatBen_Israel — Sun, 03 Sep 2017 11:50:10 GMT

Hi, I have a tif (and tfw) map that I want to be able to use offline (QML).

I have managed to load the tif as a raster layer on top of an online map, but I want to avoid it.

I I try to remove the BasemapImagery {}, the raster doesn't load...

In addition, how do I load the tfw file?

This is my code:

ApplicationWindow {
id: appWindow
width: 850
height: 650
title: "MapsProj"

Rectangle {
id: rootRectangle
clip: true
width: 800
height: 600

property real scaleFactor: System.displayScaleFactor
property var rasterLayer: null
property string rasterFilePath: "file:///C:/Projects/Sample/Maps/map1.tif"

MapView {
id: mapView
anchors.fill: parent

Map {
id: map

BasemapImagery {}

RasterLayer {
Raster {
path: ""
}

onLoadStatusChanged: {
if (loadStatus !== Enums.LoadStatusLoaded)
return;

mapView.setViewpointCenterAndScale(fullExtent.center, 80000);
}
}

}

Rectangle {
visible: addButton.visible
anchors.centerIn: addButton
radius: 8 * rootRectangle.scaleFactor
height: addButton.height + (16 * rootRectangle.scaleFactor)
width: addButton.width + (16 * rootRectangle.scaleFactor)
color: "lightgrey"
border.color: "darkgrey"
border.width: 2 * rootRectangle.scaleFactor
opacity: 0.75
}

Button {
id: addButton
anchors {
bottom: parent.bottom
horizontalCenter: parent.horizontalCenter
margins: 32 * rootRectangle.scaleFactor
}

text: "Add Raster"
onClicked: {
rootRectangle.createAndAddRasterLayer(rootRectangle.rasterFilePath)

}
}

function createAndAddRasterLayer(rasterUrl) {
var newRaster = ArcGISRuntimeEnvironment.createObject("Raster", {path: rasterUrl});
rasterLayer = ArcGISRuntimeEnvironment.createObject("RasterLayer", {raster: newRaster});

rasterLayer.loadStatusChanged.connect(zoomToRaster);

map.operationalLayers.clear();
map.operationalLayers.append(rasterLayer);
}

function zoomToRaster(){
if (rasterLayer === null)
return;

if (rasterLayer.loadStatus !== Enums.LoadStatusLoaded)
return;

mapView.setViewpointCenterAndScale(rasterLayer.fullExtent.center, 80000);
}
}
}

Re: Qml - load a tif map and use it offline, without any online base map?

LukeSmallwood — Mon, 04 Sep 2017 13:18:32 GMT

Hi Anat,

If you want to load your raster data without an online baseman a good option is to use the raster itself as a layer for a local basemap. If you change your code to declare the raster as one of the baseLayers of a new Basemap (Basemap QML Type | ArcGIS for Developers ) it should load the map at the extent of your data.

    Map {

            id: map

            Basemap {

                RasterLayer {

                    Raster {

                        path: rasterFilePath

Because "baseLayers" is a default property of Basemap, declaring a layer (in this case RasterLayer) as a child item will automatically add it to the list of base layers.

When you load a .tif file the .tfw should be automatically read for position information - assuming the names match and they are in the same directory. If your raster in your example code is shown in the correct place then I think the .tfw has been loaded successfully.

I hope that helps - any questions, let me know.

Luke

Re: Qml - load a tif map and use it offline, without any online base map?

AnatBen_Israel — Sun, 12 Dec 2021 16:33:20 GMT

Hi Luke,

Thank you very much! Unfortunately, I guess I'm still missing something...

I've copied the raster layer center x,y from the initial implementation, and now my code is as follows:

            Map {

                id: map

                Basemap {

                    id: baseMap

                    RasterLayer {

                        Raster {

                            id: raster

                            path: "file:///C:/Projects/Sample/Maps/map1.tif"

                onLoadStatusChanged: {

                    if (loadStatus !== Enums.LoadStatusLoaded)

                        return;

                    var centerPoint = Qt.point(34.89521560479882, 32.133239999999994)

                    mapView.setViewpointCenterAndScale(centerPoint, 80000);

                }
            }

It looks as if something is loaded because I get the "For developer use only" label, 
which is usually located on the map, but I don't see any map...

Re: Qml - load a tif map and use it offline, without any online base map?

LukeSmallwood — Tue, 05 Sep 2017 10:41:33 GMT

Hi Anat,

You should be able to remove the "onLoadStatusChanged" block from your code. As the RasterLayer is the only layer in the basemap/map the app should automatically start at this extent.

You may find that the app is starting at a scale beyond the drawing scale of the raster - so try zooming in to see if it appears.

Re: Qml - load a tif map and use it offline, without any online base map?

AnatBen_Israel — Tue, 05 Sep 2017 10:44:03 GMT

Works perfect!! Thanks so much!

Re: Qml - load a tif map and use it offline, without any online base map?

LukeSmallwood — Tue, 05 Sep 2017 10:47:44 GMT

Also, this call

var centerPoint = Qt.point(34.89521560479882, 32.133239999999994)

is creating the incorrect type (I think its a QML Point). You should be creating an ArcGIS Point type by doing something like:

var centerPoint = GeometryEngine.project(ArcGISRuntimeEnvironment.createObject("Point", {x: 34.89521560479882, y: 32.133239999999994, spatialReference: sr})

Re: Qml - load a tif map and use it offline, without any online base map?

AnatBen_Israel — Tue, 05 Sep 2017 11:04:16 GMT

Thanks! this is going to save me so much time...

Re: Qml - load a tif map and use it offline, without any online base map?

AnatBen_Israel — Tue, 05 Sep 2017 11:11:43 GMT

Any idea why after all the above works, the panning doesn't work anymore?

even if I zoom in and I know I have more data beyond the visible window...

Re: Qml - load a tif map and use it offline, without any online base map?

LukeSmallwood — Tue, 05 Sep 2017 11:16:03 GMT

Do you mean that you are unable to pan outside of the extents of the raster data-set?

Re: Qml - load a tif map and use it offline, without any online base map?

AnatBen_Israel — Tue, 05 Sep 2017 11:25:50 GMT

Not able to pan at all. I'm looking at a small window, smaller than my raster image.

I thought I would be able to pan, and when I get to the edges, get a blank area.

But I can't pan at all...

Re: Qml - load a tif map and use it offline, without any online base map?

LukeSmallwood — Tue, 05 Sep 2017 11:27:43 GMT

That doesn't sound expected - would you be able to post your code and I'll see if I can reproduce?

Re: Qml - load a tif map and use it offline, without any online base map?

AnatBen_Israel — Tue, 05 Sep 2017 13:04:38 GMT

I figured it out. I've created a MouseArea to report mouse coordinate and it blocked the panning.

If I disable the MouseArea the panning works again.

Thanks again for everything!!