ArcGIS is a CAD type bit of software which in turn deals mainly in vector graphics of lines and polygons to make maps and these, of course, scale well. Its running from a data base which has a pedigree of being able to cope with many users hitting the database in rapid succession. In terms of making the kind of maps you see in Ordnance Survey / Road maps and architectural plans it would do extremely well. In a client / server set up as you describe you could either request a part of the map and let the server send that section of the map down to the smart client where its rendered out or you can render the bit of the map on the server and send down just enough info to render that screen view only on a more dumb client. If the user moves a little then in the first instance the client says to the server I have moved a little, server says yeah ok nothing changed and now go and rerender that scene. Hardly any bandwidth. In the second case client says I have moved a little, server grabs the map from the database again and sorts out a draw list and sends that back and dumb client just renders it again. So in the first case the initial download is large but from there on its small updates or in second case its uniformly middle sized info from the server down to the client.
Now the vast majority of RPG maps are not vector but bitmapped. Ok so a very select few on here use vector stuff - GP with Xara, and some of the CAD, Space ship designers etc but it must be 90%+ of people here use PS / Gimp or whatever to create a bitmap. Even for those that did use a vector format I dont think that many of them would have maps in ArcGIS format. So you are basically cutting yourself off from the existing maps and creating a new world exclusively in GIS formats.
Now if you can embed bitmapped images into the vector GIS formats then you have those maps. Now heres the thing. If you have the smart client option then its a huge huge download for all the bitmapped images once but then its fast to update - this is the MapTool / ViewingDale / FM8 approach. If you have the dumb client then its going to more like ScreenMonkey where it uses your web browser as the client (i.e. kinda dumb) and so must send the portions of the image down each time to make up the screen. In most cases these VTTs use a fixed backdrop image and send down only the moving bits so that it can cache that backdrop image.
So if your going to do a whole world then you really need the smart client way of doing things or else the bandwidth is going to be massive. Since it seems that this ArcGIS demo was using the browser then its not likely to be or maybe its unable to use RPG bitmapped maps. But lets for one second assume it is smart. At some stage the server is going to have to send down all those images required to render the map. You cant avoid the issue if you want to map with bitmapped images. So this is a necessary evil for anyone who wants to do it this way and I think I have described why for the case we want its the only way.
So because everyone must send them then lets assume that you have took the pain and got a load of images downloaded. Its about 5Gb or so. What you would like to do now is reuse as many of those images in as many situations as possible so that you can have different things made out of the same images. So think of castle. We could have some crenelations and make walls and tower out of the same bit. Once you have laid out 20 or so to make a square tower then you would like to put ten towers down you need to set that tower crenelation set as a group and use them as one tower and put down ten towers which is 200 crenelation images. This hierarchical grouping mechanism is what viewingdale is all about and its capable of rendering about 100,000 of these images per second so it can make up a map out of lots of small bits of things. Its likely that a GIS program would do it this way too but its definitely not possible to get your browser to do it. So the system that you have highlighted must render them on the server and send down that post rendered screen. That does not scale with lots of users. So as more users join up on ArcGIS it would slow down severely or, as I suspect, it wont allow bitmapped images.
Because in ViewingDale you only have to say where the ten towers are and how to make a tower the amount of information that needs to be sent down per user per render is tiny - in the hundreds of bytes not tens of K or megs of image. Thats why when you make a change to the map its updated on all the others so instantly unless the change is to add a new image of which then that image has to be sent to everyone. So in reality the real scalability of ViewingDale is in the server upload bandwidth which for me with my asymmetric bandwidth is criminally low so its never been tested to destruction.
ViewingDale connects to other copies of the app. Every app is capable of being the server or a client. When a user connects it as a client to another copy as a server its running in that smart mode. You can also set up one copy as the server and make it serve web pages too. In that case it renders the part of the map requested and then it sends a PNG image back to the web browser as a client so that its more like Screen Monkey or for when not everyone in your group has a copy. But as said that is slow and does not scale very well but it can be done. You cant edit the map on the server using a web browser as a client tho.
When editing the servers map with another copy as the client in the smart mode. One person at a time gets to edit the map which is not as good as using a database. There is what I have called the edit baton which you grab and keep until you give it up. When your editing the map everyone else sees your username as editing the map.
When I say editing the map I mean you can edit any thing in the universe that the map is displaying. So you can edit a pub whilst someone else subsequently takes the baton and then edits a battle map in another area of the map. So its not like your stuck with a battle map and everyone has to deal with that before you go to another location. So its world sized editing at any zoom level just like you wanted.
The number of concurrently logged in users is limited but I think the limit is quite high. I don't think I have ever stressed it with real internet based people enough that I broke it. Its bandwidth limited more than CPU limited cos really, the server doesn't have to do very much. In smart operation its all the clients doing the work which is why it scales well.
I hope that gives you some insight into how these things work, how mine works and some of the issues involved in it all. I have custom built ViewingDale to tackle this precise problem using every available optimization that I know to make that job as slick as possible. If your ok with a vector world and not wanting to use existing peoples maps then sticking with vectors might mean that my solution is not as optimal as it might possibly be. But I tackled mine from the point of view that if you want a lot of people to add to your world then you have to sell something which does not need $5K or custom format maps etc. I can see why govt agencies would need it ArcGIS way but I don't think with RPG nuts it would be a goer. I'm all ears for opinions and comment tho. Id love to know why people haven't taken it on board more than they have.
I dunno if you have seen this vid. I post it now and again cos it covers a lot of what the app does. If connected with multiple users into a server then you could edit the position and size of any bitmap or icon on this map at any scale together - but one at a time.
http://www.youtube.com/watch?v=qELcbKXdRm8
Reply With Quote
