QGIS Temporal Controller with WMS-T layers
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Number of Parts | 351 | |
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License | CC Attribution 3.0 Unported: You are free to use, adapt and copy, distribute and transmit the work or content in adapted or unchanged form for any legal purpose as long as the work is attributed to the author in the manner specified by the author or licensor. | |
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00:00
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00:19
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01:16
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10:16
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13:31
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Transcript: English(auto-generated)
00:00
Hi, all. In this session I'm going to talk about the QGIS temporal controller and how you can use it to visualise and access WMSD layers. So just a brief background. This work was done under the fund from the Government
00:29
of Canada under the contract of MapGears. And my name, as I've been introduced, is Samuel Moksambwe. I'm a senior software developer from Katoza, which is a South African company
00:44
that deals with providing services in free and open source softwares. That includes training, software development and we also do maintenance for the existing GIS systems.
01:01
Also QGIS core and PyQGIS developer. That means I contribute to the core features of QGIS and I also write plug-ins to add some new functionality in QGIS.
01:20
I'm going to cover the following topics. I'm going to briefly introduce the WMSD specification for those who do not have an idea of what WMSD specification is. I'm going to talk about the temporal controller and the QGIS temporal controller modes. Then we're going
01:40
to look at how you could add and access WMSD layers inside QGIS and then I'm going to show briefly the animations that you could make using the WMSD layers. And I'm going to touch a bit about the temporal controller API. Then I'm going to finish the presentation.
02:05
So just briefly about QGIS, I'm sure a lot of you already know what QGIS is, but for those who don't know what QGIS is, it's the GIS software that allows you to create, edit and analyse your special data. You could also create maps and visualise maps
02:27
inside QGIS. QGIS supports a range of data formats. You can use it to access vector, raster, mesh, NetCDF. And recently QGIS support has a core support for temporal
02:44
data, which includes the WMSD layers. So the WMSD specification is an OGC standard that was designed to help serving WMS layers that have time support. From the slide there,
03:06
you can see one of the layers served from a Canada metrological service. That's from the QGIS application. So for those who don't know how to add a WMSD service, so in QGIS
03:29
you have this browser panel. You could go and use the WMS or WMSD provider. So you can see on the left there, that's the UI for the browser panel. And then after
03:47
you click new connection there, you could use the dialogue on the light. You could use it to add the name and the URL. Then when you click okay, a new service will
04:03
be available for you in the QGIS. So the QGIS tempo controller, so I would like to incorporate data inside QGIS in the most efficient way. This work as I mentioned before
04:29
was funded by the Government of Canada through the MapGear contract. It was developed by Cartosa together with Northrod. Before QGIS there was a plug-in called Time
04:52
10,000 downloads. It was developed by Anita Gresser. It had certain limitations which
05:05
the QGIS tempo controller handled. They were reserved in the tempo controller which resulted into the plug-in developer to retry the plug-in and provide more support for
05:22
the tempo controller. So the development of the tempo controller was, so the main part of the tempo controller was finished on May 2020 and the first QGIS version that
05:42
had tempo controller was QGIS 3.14. I'm going to talk about the tempo controller modes. By default the tempo controller has a disabled mode, navigation disabled mode. When you now download QGIS, the tempo controller is disabled by default. When you access the
06:08
tempo controller using the icon, you can see that there's a clock icon on the toolbar. It will pop up in the following mode. That means the tempo controller navigation is
06:24
disabled and this was designed so as we don't want to enable the tempo controller by default because it might make users confused the first time. There's also a fixed tempo range mode which you can use to filter and show only the layers
06:48
that fit in that range. So let's say you have layers that range from the 23rd to the 24th and you want to fit out only those. So this is the mode that you want to go with.
07:05
And the last mode is animation mode which is used specifically for creating animation visualisation. So you could have a list of layers, different layers and when you are doing this is that when you are stepping through each frame as you can see there, the QGIS
07:26
tempo controller broadcast a tempo range that you can use to change the data. So any layer that will match the broadcasted tempo range, it will be shown in the QGIS
07:46
map canvas and any layer that doesn't match that specific tempo range will not be shown.
08:02
On the WMST layer now, we have seen that we have certain modes with the tempo controller but we want to see the influence it has and the effects that it has inside with the WMST layer. So for those who are not familiar with the WMST layers,
08:26
this is how you could add them. So you need a service that you could add there, you could just slide kick and add the service as I just shown on one of the slides back and then you could navigate through the service and you could select the layer.
08:46
So the example that you are seeing there is the line for data that has been broadcasted each month from the digital earth service. There is also another way to add
09:03
the WMST layer, through the data source manager which you also connect your service provider and then you load the specific layer that you want. After you add the layer, you will see that there is a clock icon on the layer item on the light
09:29
side here that will tell you that the layer that you have added has tempo capabilities and it's possible for you to use it, to use tempo controller on it.
09:44
So not only the WMST layer will have that icon, any layer that has tempo capabilities, a vector layer, elastor layer, net CDF or mesh. So if you just append to add the layer and then you see this icon, the clock icon there, that means it has tempo capabilities.
10:04
So this is one of the features that the tempo controller has added inside QGIS to automatically detect each layer that has tempo capabilities. So for the WMST layer there is a specific
10:22
section that you could use to manipulate and get data from the WMS service. So what you are looking now is the layer properties which you could get from the added layer that you have shown you, we have tried to add in the past slide.
10:46
When you go to the tempo tab, you will see that there is dynamic control here. So this is an option that you check if you want the tempo controller to have
11:00
control on the specific layer. If you don't want the tempo controller to have control on that specific layer, you can just disable this. So for the WMST layers, so for those who are familiar with WMST layer, there is some instance you just want to update
11:21
a single layer and not necessarily broadcast the whole, or should I say change the whole tempo range on the tempo controller, maybe I just want to deal with the specific layer. So you can just disable this dynamic tempo control and then use the settings that you have been provided there. And you can see that there is even a label that will
11:45
alert you in order to use these settings, you need to disable the dynamic tempo controller. One of the settings is the time slice mode. So one of the options that you could go with is use the match to start range, which you use when you, so when you click, when you click
12:09
here to disable the dynamic control, you have start and end dates that you could use to input, and then after you input those dates, you want to specify whether when you query that layer,
12:28
you want it only to use the start date. Another, there are different size modes, you could choose to include both of the dates, you could choose to include only one of the
12:47
end of the date, but there is also a setting for ignoring the time components, maybe you just want to query the layout using dates and not necessarily using the the world date and time. There is also an option number three for reference time.
13:08
So in some of the WMST layers, they support reference time. So for example, this forecast data where there is a date that the forecast has been done, and then the date for the forecast is to happen.
13:24
So for the server that supports those kind of layers, that's the setting that you want to use. This is one of the examples that WMST layer using the temporal controller
13:44
and the temporal controller is in the animation mode. This data is from the Canada meteorological service. As you can see, it's looping through
14:00
different times of the days and it is showing the air temperature on earth. This is another example still using the Canada meteorological service layers. So this is for wind waves. You could still see that it is going through
14:28
a different set of dates. So to achieve this, first of all you need to make sure that the temporal controller animation mode has been enabled and then you make sure that
14:44
the animation lens matches the lens that the layer has broadcast that it has data with. After that, then you can just use the play button to go through and query different
15:06
different WMST layers. Originally we planned to show an example of a simple plugin that we wanted
15:21
you to show how you could, for plugin developers, how we could tap into the temporal controller API and use some of the features that it has exposed, but due to the limitations of the presentation, we are unable to do that. But there is a temporal controller API
15:46
that's available on the QGIS documentation. So if there's anyone who is interested in doing or getting to know how they could use it, they can just reach out to us.
16:02
Yeah. So all of this work is available under the QGIS main source code. And if you use any of these features that I have just shown you here, you could just open, if you have any issue while using one of the features that we have just shown here, you could just open
16:23
the issue inside that link, which is the QGIS issue page. These are the resources that are available. The QGIS I think most of you are familiar with and the WMST specification
16:46
and for the metrological service of Canada, because I have shown a lot of the data from them. They have a lot of WMST data that you could play around with. Just to summarise this, the temporal controller has enabled QGIS
17:07
to handle temporal data in the most efficient way. Because without it, we would have a lot of plug-ins, each of the plug-ins with a specific scenario trying to handle a certain
17:24
data provider. But right now we have a temporal controller which all logic that will be added for any data format provider will be there to the API and to the structure that the temporal controller has set in. And also the temporal controller has enabled QGIS to be users to
17:48
use QGIS to also do visualisation of different, if not all, temporal formats, I mean data with temporal capabilities.