A User-centered Design for Interactive Masking Capability within Web GIS

Video in TIB AV-Portal: A User-centered Design for Interactive Masking Capability within Web GIS

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A User-centered Design for Interactive Masking Capability within Web GIS
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Open Source Geospatial Foundation (OSGeo)
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Portland, Oregon, United States of America

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This presentation will discuss the design of interactive raster masking capability for a web-based geographic information system (Web GIS) from the perspective of user-centered design. A case study will be presented by analyzing and discussing specific aspects of the user-developer dialog within the context of the software development life cycle. The presented case study will take the audience through the development of an open-source Web GIS software architecture (MapServer, PostGIS and OpenLayers) with particular focus on how the masking functionality was designed and implemented. Software engineering techniques informed by iterative cognitive walkthrough allowed for a dialog between Web GIS production and consumption that led to a more usable and useful cartographic interface. Key findings from this case study will be presented.
Keywords Usability User-centered Design Web-GIS Cartographic Interaction
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so that you for coming my name is Derek Morgan on and of the minute the presented on users in the design for interactive have massive capability within web as get everybody here we hear me OK get on and this is the paper we submitted on the academic track and this presentation based on that and so I should mention my 2 other co-authors Mark Phillips and that Hutchins Marcus here so so
the story of this this presentation revolves around on implementing masking capability with an 0 0 and existing Web GIS so that existing Web GIS and with region we are written in flex API with the back has pretty much been an open-source stack since its inception so as the growing season was heating up in our 2013 on we were getting a lot of new feature request and we have already made the decision that we're going to try and limit of adapting the Flex code and data to go with OpenLayers in so the the image below shows the OpenLayers implementation of that and saying you were which I'm as you can see it look very similar and there was a goal to make the most of you
of so a little bit about the force change assessment you're which is a Web GIS which I'm working here on the peace in our motives data that so far been preprocessed by folks said of great and on dropped off on our servers in that notice there's been preprocessed and delineate changes in India of the normalized density patient and so that's actually an index that can be used to assess the greenness of plants and trees and century and I have a link here so that you can actually go to to find out more about the science behind and treating those data products that's not at the actual focus of this presentation about the their
products meaning the idea of products our they 231 Mirapex pixel resolution and so you have an idea of how much ground that covers on it took a couple football fields that European football field stack them 3 times it would be bad for you also have a picture illustration of with the size of the
text of this is you can see half the legend of the 1 of the players this is same like and its reuse throughout the essentially show that per change in India and that used by the for scientists to all bases and biology of the the layers job in Web GIS trying figure visualize where changes in EVI occurring in those gene user based on the baseline products and the 2 the 3 main base parts they use it to 1 year baseline 3 baseline all your baseline going back to when the project started on there other other baselines they have the the the the primary ones utilized so I have a
demo and then I decided to take
the current working Indian
on last year In illustrate on decided to so using this web GIS
to it we then you get
changes in expected thing like appears crashed so if you
start talk about yourself as bad as they are and like the driver for the trajectory of but basically it was going to be on as consuming
today coast of New Jersey and show you the tree of Cindy landing on the the i values and then the post Sandy of hurricanes and in the end of which you can see whenever you look at that is a a distinct change in the on symbology at the blue and green goes from pretty stark red on that's the sort of thing they use set for 2 explore the data in the user for a lot more than looking at just certain strikes they look at a pest infestations like him walking mark Willie intelligence and they also look at fire currents and maybe even use it to locate where tornadoes that tore through a national forest and nobody reported that there is a the at the end of the so the software architecture is actually of as I mentioned that the data cited it's been faster G since its inception its its map server the server and getting styles in the and running on Linux installation which is actually assiduous as flavor the end of the then for vector data already where users post just was just post grass and and on top of that as an engineer was flexor now we've gone to to of OpenLayers and on that's a process of like a year-long process of migrating to the New York is so 1 of the request they came up that prompted him to look at going to OpenLayers was on the ability to mask these rostral layers on the floor of it is greater than this the video the after all this is on the string across the country in the world but I am it very good year home viewing pleasure have been and I'm going to call 1 of the areas of going to the archive and even the 2nd phase of the of the 2 years of the the the the the mean of that genes that we have to break the mass of the ontology and so we ended
the knowledge that we have In the next in order of of where the higher end of all right and so cannot come
layers of the work in the center of a of things that
way to the essentially what what is so that we use the cost of inactive so in office work was you and you the the yes
and then they in may account for that 1 as much as possible and there's definitely seasonal change but with N O 4 they carried on 24 day period it's not gonna be that start on but yet throughout the season there are definite changes in EVI what
is the i the masking demo that I have which is the area what is
that it just look at the Mount Hood
National Forest the the idea is that there was actually would appear to me to be a disturbance and so on you need to that
experience and this exactly with the foresight uses for they start looking at 1 of the ancillary data can tell me what causes disturbance in this is east of Mount Hood not here and so 1 of the things they go to look at a lot of times as fire and so that was 1 of things I in it turns out in 2013 if you look at the set fire points there were a large number of fire there on and that's exactly what's going on this is a pretty recent of disturbance in the
identifier and the use on fire which is good feature of all and find out more about the fire of the same of
the last and so that words so
about I think this is the thing really what it it seems to me
that I and you get this is most of inquiry that the
worst thing about the example of the
mass of the areas in the hands of a half and the anatomy of the pixels of the other 2 areas in service the
the now another thing I should mention that and you're
going to this process of developing this for them and we were using what I described is an iterative of design process and so we would build on essentially a prototype that it's masking functionality and give it to them and they would tested out and go through the typical steps of forest disturbance detection and then give us feedback in and we wish to get feedback go back and you know trying to implement that and so we have our particular contractor set such that we were allowed you know we could take that into the project scope and that's not always feasible sometimes you have to do something like that typical traditional waterfall but they you know often after they've seen in their national happens Christmas vacation where mediated in 1 of these iterations you know I'm just getting a list of all the things that don't work but is not always that more to the point paper in the next 2 slides is what doesn't work about the design the UI design and so moving on to that and
this is the 1st this time we came up with for the unmasking of functionality in I call this layer level masking and so because map server has the ability to mask and INEC she treats that mass is a layer on we designed it such that the of the actually tied to the light in a scene pretty intuitive to us i and you know to them at the time to but once they start using it to actually going to look at the force experiences the realize that this is not working for us what's going on here but what would you have here where th n of the Act also turn that layers last time and so they ask for something more like this which is
the is disconnect in a sense the mask from the villages themselves and have him the more centralized and tackle I call this global people asking and so the idea here is that by the way asking any other layers they're maskable of would get that maps and could in the same token the layers that you of that turn on and turn masking should also be honest no
so at 1st blush they may not seem that complex this began looking at the use cases and 1 needs to follow by separating the mask from the layers so we can begin to get the idea itself difficult coding something that can be noun so here's the use cases these are pretty basic just activated deactivated ask I'm looking at the later in adjusting or sharing and that's another feature of this tool visibility shared state of the
of the map and we do that with the sharing of just a URL that you can copy into a browser e-mail them
so here's a little more functionality on the training and use case that they would use the ability to adjust capacity and so you need to write additional code you adjust the opacity of the mask also top of that and if you will more idea the additional functionality into account for with this this is another way to
illustrate that this is a of Sequence diagram of where you've been where you have time this across the x-axis in you see you at how the idea of activating appear in the last and out its subsequent interaction with a layer of the of the direction that the actual function so we use to you know that that on
this side of the channel more about the to and 1 of the things on the and here is the same text in the file server that our method is so we see that there is a the actual that's where you have a lot of the other the and we asked whether it was possible so in these layers themselves but the real question from the UI standpoint this whether this is a one-to-one relationship or a one-to-many relationship and in our experiment with the one-to-many fires mean I'm asking are applied in many ways
on in trading evolution was the but for the user with the trip another too much of the now the architectural challenge they came up after implementing masking there we hadn't really run into before was this intuitive on exponential use of load on a server so if you think about it on when we would load the map before if we had just 1 there are 2 layers checked any time we're pan or change the extent we would be sending get map request on 4 2 layers only but once you begin stacking the mask on top of that it exponential increase so the load on the server exponentially increased right so for example the 2 layers the mass change the extent they now ask for the 6 you know that that's the way it used to be 2 and so after we implemented this we began to realize certain from optimization challenges that the need to be addressed
and the you know and you just acknowledge that attack on so the research station which is a national North Carolina there the primary clients of this product here without them we wouldn't be here so so the thank
impressionist so you're actually pre rendering WMS layers and then serving WMS layers as your masks of my giving them right where the masker actually on there are geo tests just like all the other layers OK so they're just geo tests with 1 1 starts here is basically and so the ones of the mask in those wondering if you considered of filter approach rather than a mask approach where you you send filtered so like queries to the server and generate grip pouch render on the block render the graphics on supply you need for so so taking it from the front like using right greater openness that's the 1st thing we consider actually outsourcing I considered an avid began researching it and even road on uh always Geoforum and I just can't find a solution is going down that road and to below to filter the the Rasta layers of thinking through and if you have an idea of how do look to talk to you afterwards it may be more efficient potentially any other questions the thanks for making a clear


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