Archive for July, 2006

Free GIS or The value of a GIS

July 31, 2006

Many free GIS have been developed and enhanced in the last years beside the commercial products. Normally they are available as OpenSource. I can hear you scream and shout: “Oh my God! No more OpenSource!”.

That a system like GRASS was developed by the US Army plays a dicisive role. You can see at first view, that it was not developed to look nice, but the functions underneeth for analyzing bitmaps are unbeatable. GRASS is successfully used for the simulation of flood and forest fire. With the sampledata you can get a good overview what you can do with this system.

For my purposes systems like Jump/OpenJump and Quantum GIS are better suitable because they are vector-based. The features of any objects are shown in listings for one or a group of objects. Both systems have a Java-based gui. They handle data in an own format or one can save a layer as an ESRI shapefile, to mentione a well-known format. Further on they can both be connected to PostGIS (this is even true for GRASS) to read and write data in special tables.The objectfeatures can than be listed in the application. The connection is established by the GIS. The layers will be displayed in the gui. Datasets can also be limited by SQL-statements, which you can use during connection-process, to filter the objects you really need out of the whole.

I will come back to the database connection later on. Connecting to an external database gives also benefit and flexibilty to the non-GIS user. This point is also true for the commercial products, which have software interfaces for different database systems, too. The user can access an datapool which is maintenanced and administrated by a central department. To do so, the user does not have to use GIS. Pure alphanumeric data can often be accessed in an easier and faster way using special reportingtools. With the PostgreSQL-extension PostGIS you can do a spatial query without using a GIS — if you only know the correct syntax. The thing about GIS is identification and showing of data which cannot be brought in this dependency by using listings and tables. Listings and tables are good use if you want to analyze alphanumeric data. But every time an object comes along with geospatial information you can only get full potential if you identify and analyze the spatial relation.

At the moment I’m working on real estate information, like land parcels, buildings and houses. I’m in charge of the GIS. Beside our SAP, which is surely first choice for housing industry when it comes to interests based on the needs of tenants and buildings, the GIS is of real great use. Nearly 95% of information in this buisiness is geospatial referenced, so all of these information can be viewed in the application related to a single object. Based on information about land parcels, buildings and maps more information dealing with special contracts, debits and special features can be displayed at their correct location. The user can see at once what to consider about the objects. A topic which has gotten weight over the last years — in germany — is the correct billing of e. g. cutting grass and trees in the additional expense for the tenant. That means billing of all the work, that is done in the backyard and in front of the house with the plants, grass and bushes, done by an external company and not the real estate company itselfe.

All this information are — as soon as they are entered into the GIS — available in the system and can be part of a report. Additional expenses could not be prooved by the companies for years. Now the GIS knows areas and lenghts precisely. These data can be processed in internal or external applications to get the amount of expenses for a whole town or just for a single tenant.

By connecting to an external database the user can collect some information in GIS and extend it by non-GIS information that are also in this database. This is the only way to create a qualified report for objects that have a spatial dependency. As long as our data is located in one street, we can handle their dependency with a normal database. But a GIS gives you more flexibility for reports that apply to an area which you cannot describe with alphanumerical information. Economic units, quarters, colonies or related information can be added to the baseinformation of an object without problems. But to get them you have to look at a map and if you try to get a subset of it or a spanning amount they may be incapable.

I stop my post at this point and will go on with some more details and examples on single topics of the things written above.

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Your GIS – the unknown being

July 31, 2006

Well … many people doesn’t care about what a GIS is. Many of them do not even had any contact with that kind of software. Nevertheless there surely are a lot of people which could use it for their advantage.

But one after the other!

GIS is the abbreviation for Geographic Information System. Such a software is always used where information is related to a geographic point or area (geospatial data). These systems were originally used to represent pipelines or buildings in the industry or real estate sector. With the development of the systems they could also be used for planning projects and give some strategical evidence. Systems like GE Smallworld GIS were classic representatives for the group of asset management, which can today be used for strategical use or support as well. A system like Grass was born in research. Developed by the US Army, it has a lot of tools for working with bitmaps (e.g. air photographs). The main use of these systems points out that there are several GIS for different use. On one hand you have a verctor-based approach with bitmaps just for orientation. On the other hand you have high-resolution bitmaps with information for every pixel and vectors and new bitmaps only as an result of complex queries.

Smallworld as a commercial product comes along with a great expense factor. Licenses and support are not cheap. Instead of that youget an very professional system which accomplishes nearly every wish one could have. The rest can be programmed! 🙂 OpenSource and freeware can even be interesting for you, because of the great amount of mature functions and the possibility to connect the GIS with a free and capable database system. And that works even, if you have a lot of data and maps.

With one of the next posts I will go more in depth.

A GIS usually comes along with a grafical workbench, called a gui. The user or admin can use this to handle the systems and it’s functions. A lot of the systems have an AddOn or connection for a webbased desktop. Smallworld comes with a standalone webservice other systems can be connected to the UNM mapserver.
Every system works with an internal or external database (e.g. Oracle, PostGIS, MySQL) to manage the alphanumeric data. But it has not to be a real database. Some systems work with ESRI shapefiles or GML/XML-files. It’s difficult to connect to Smallworlds internal database system from outside the GIS. Other systems use external database systems like PostGIS and Oracle spatial. At the point where a number of users should use the same data, the system should be a client-server-application to devide data (backend) and application (frontend).

The next posts bring hints and approaches to the interested reader — hopefully you — to point out the differences between the systems.

For every company with geospatial data there is a great benefit to have a closer look at these systems for making the work with their data more easier. No existing database has to be thrown away and no data has to be kept redundant. With a clever integration the freind of MS Access can still use its queries and reports. And VBA programmed macros can also be used after it. The other users get a noticeable surplus in terms of increased efficiency. Even if I always use this term related to computers with an unpleasant feeling. (Quote: “Computers help us with problems, we would’nt have without them.”)

If you have a look at the so called geomarketing [in engl. it’s Business GIS but it doesn’t mean exactly the same] you should find no serious company which has no GIS — maybe it’s integrated into their reportingtool(s). But later more …

Setup

July 31, 2006

Meanwhlie I’m working with GIS for about ten years and have made a lot of experiences. So I would like to put some of my ideas, projects and maybe interesting thoughts in this blog.

When I write about commercial GIS products, I will write about GE Smallworld GIS (yet still version 3). That’s because I’m working with it on my job. Beside that I will write about free or open-source products like GRASS, Quantum GIS and Jump/OpenJump. In this context I have to write about databases like PostgreSQL/PostGIS and maybe some MySQL-stuff.

Surely there will be some writing about topics that don’t have to do with any of the above.

For I’m german, you will please excuse my errors and I hope you can get the sense of my posts. 😉
Don’t hesitate to write a comment. Your opinion is always welcome.

Important Note!

Talking that much about GE Smallworld GIS has nothing to do with some kind of advertisment and any profit for me, selling this product. I do not sell this product and I do not have any benefit from doing avdvertising. The same is with the other product.