In Image Web Server documentation, for bounding boxes or coordinate references, we often refer to TLX, BRX, TLY, BRY. TLX stands for "Top Left X-coordinate". "BRX", refers to "Bottom Right X-coordinate.
Other applications may instead use different terms, such as MINX and MINY.
How do the two systems relate? Well, very easily, the mapping is found below:
MAXX = BRX
MAXY = TLY
MINX = TLX
MINY = BRY
So, you just need to substitute the values when dealing with different systems. For example, an OGC WMS Service will use the MINX terminology. Simply translating the IWS coordinates will allow you to easily communicate with WMS services....
If you didn't manage to attend the "Throw Away Your Tile Cache" webinar, here are the powerpoint slides i used, as well as a video recording.
It was a real pleasure to show off the hard work of the IWS engineers in this webinar. The team constantly impress with their mantra "performance".
Hardware resources and hardware speed are just like money. There is never enough! You always want faster! Even with the multi-core systems that are out today, you still want more speed. Yeah, your new computer might seem fast now, but give it a week (or a couple of days)...
This is why I really, really like the IWS development engineers. They will go to amazing lengths to get the most out of hardware.
Many engineers or engineering teams out there don't have this sort dedication to performance. They just think that more hardware can be bought. But, we know, that there is never enough. Even if you can afford it.
Getting the most out of your hardware is definitely going to help in todays economics. Regardless of what your hardware vendor (or maybe IT guy) says!
So, please enjoy: PowerPoint - Throw Away Your Tile Cache (~2.2 MB) Movie of "Throw Away Your Tile Cache" (~50MB Windows Media File)
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Image Web Server can now serve your vector data at the same blazing fast speed it serves image data!
Next Tuesday, 25th of August, Richard Orchard, Product Manager of Image Web Server, will be hosting a webinar previewing this exciting, upcoming feature of Image Web Server.
The webinar will show you how you can effectively serve both image and feature data with Image Web Server at unbelievably fast speeds. In particular, new features of the "optimized tile delivery" functions of Image Web Server will be reviewed. A comparison of the new technology against a "tile cache server" setup will also be made.
If your organization is interested in creating a public access website, this webinar will show you how easy and inexpensive the most powerful geospatial serving engine is to implement....
Google and Microsoft Virtual Earth both use a Spherical Mercator projection for their geospatial data. This is represented by the EPSG code of 900913. This particular coordinate system converts the earth into a perfect square. This fits perfectly with the square image tiles that are delivered by the Google and Microsoft Systems....
Our development team, on top of getting ready for a big release in the fourth quarter, has released an update to our popular ECW Plug-in for AutoCAD. The plug-in allows massive images to be viewed with ease in an AutoCAD environment. The images can be accessed locally (in ECW or JPEG 2000 format), or even better, via ECWP from Image Web Server.
The new version resolves some issues with AutoCAD 2009, when it had the latest service pack applied to it.
At the same time, the developer looking at the AutoCAD plugin, David Carter, also managed to extend support to AutoCAD Map and Map 3D. There has been some demand for this in the past, so I am hoping that this inclusion will make a few people happy out there.
You can download the plug-in from: http://www.erdas.com/tabid/84/currentid/2508/tabview/downloads/default.aspx
Specifically, you want to get the file: AutoCAD 2007 / 2008 / 2009 + AutoCAD Map 2008 / 2009 ECW JPEG 2000 plug-in 2.3
We are aware that the install process may not be smooth for people with a custom install of AutoCAD. If you fall into this category, we have some simple instructions for a Manual install of ERDAS AutoCAD v2.3.doc
The plug-ins are provided free-of-charge, and we hope you find them useful. If you have any questions, please post them in the ERDAS Community Forum at http://community.erdas.com/ .
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J2i files speed up the delivery of JPEG 2000 files.
J2i files are an "index" of the JPEG 2000 file. Indexes of JPEG 2000 files can be many hundreds of megabytes in size. J2i files are automatically created by Image Web Server and used to speed up decoding and lower the memory overhead....
WMS or Web Mapping Service is a popular way of distributing geospatial data.
However, something that has been showing up more recently is that people may overlook the performance gains they get with simply using client-side asychronous access. Instead, they make one of their server components work really hard and subsequently slow down their entire application. Cascading Services through a single server.
In the diagram you can see one WMS Server requesting information from another WMS Server, then sending the combined information onto the client application. Whilst this may seem "convenient" to a system administrator, the solution is also likely to underperform. One service is going to be dependent on the other service, and do some unnecessary extra work. On top of this, often the requesting server doesn't just pass through the information, it saves the information to its own system, then passes on the data. This doubles up the work needed to be done to present the information.
A better way to get the data to people faster, is to make "asynchronous" requests to the different services, from the client. Asynchronous delivery of geospatial data 
In this instance, neither service is dependent upon each other, and neither service has to do more work than it needs to. By saving your system resources, you get to save time, with faster responses. And, by conserving your system resources, you can do more with your existing hardware....
If you create web-based GIS websites without using the browser plug-in that provides ECWP ability you need to be aware of something very important.
All modern web browsers impose a security restriction that prevents a script or application from making a connection to any web server other than the one the web page originally came from.
So, if your JavaScript file comes from http://iws.erdas.com/ it can only talk to resources from http://iws.erdas.com/. 
It cannot access resources from another domain like http://www.yahoo.com/ or even http://www.erdas.com/ . 
This can present a challenge when we use a purely HTML and JavaScript front-end to imagery or GIS data. We may have these resources on different servers and domains. For example, I might serve my web page (html, JavaScript, etc) and imagery from one server, but my GIS information from a different server. Given the above limitation, this isn't available by using just a browser. So, how do we get around this.
To be able to request data from a source apart from the scripts orginating domain, we use "server-side proxys". These server-side applications reside on the domain that the javascript is served from....
If you are wondering how to create a website using Optimized Tile Delivery, or OTD, I have some very good news for you.
OTD sites are created using the same website API that are used to create other Image Web Server sites. It is exactly the same as when you are creating DHTML sites, and only marginally different from creating ECWP high-speed streaming sites.
The only real difference is that the file you are passing is a .OTDF file.
So, to create your OTD enabled site, you just need to force the page to use the DHTML control, by setting the correct browser cookie:
setCookie("NCSPluginInstallMethod", "HTML");
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If you are using the "NCSCreateView" function, that is all you need to do.
If you construct the map control directly, you would need to make sure that you instantiate the NCSJSView, for example:
Imagery can be stored, and served, from anywhere on your network.
You do need to be aware of some simple network and security considerations.
Just like you "login" to your computer, so does the applications that you use. Sometimes they just "borrow" your login, but other times they use any number of system defined "user details". This is particularly the case for any server application.
Image Web Server operates under a defined user account. This account must have “read” access to the image files in order to serve them....
For Windows based installations, before installing Image Web Server you will want to check that you have Internet Information Services installed.
Internet Information Services is the free web server that is packaged with the windows operating systems....
Once again, Chris Tapley has been busy, and has developed some simple ways to add IWS data to ArcGIS based websites.
The integration is in two parts: - ArcGIS WebADF ImageX/OTDF DataSource
- ECWP and ImageX/OTDF layers for the ArcGIS REST JavaScript API
The “ArcGIS WebADF ImageX/OTDF DataSource” requires the following to be installed on the machine: - ArcGIS Server 9.3 .NET edition
- Microsoft Visual Studio 2005
It is possible to just deploy the Web Mapping Application to an ArcGIS server machine without VS2005 installed, but for development purposes VS2005 needs to be there....
ECWP is a high-speed streaming imagery protocol provided by Image Web Server.
ECWP allows a single, entry-level server, to provide 1000's of gigabytes of image data to thousands of concurrent users that are using different web, desktop, GIS, server or mobile applications....
OpenLayers is an extremely popular framework for creating web-browser based mapping applications.
A developer in our Perth, Australia office, Chris Tapley, has created a "ECWP Layer Type" for OpenLayers. So, if you are using, or want to use, OpenLayers, you can now easily add an ECWP layer.
An example of this can be found at: http://iws.erdas.com/OpenLayers_and_iws.htm
If you want to create your own OpenLayers / ECWP enabled maps you can download the code: openlayers_and_iws.zip....
In the case of Image Web Server - 600 clients can be requesting maps, from a repository of 500GB+ of imagery - and all get sub-1 second response times. In fact, the number of clients can grow into the thousands before the response time begins to go over the 1 second mark. The server hardware: A dual Xeon CPU, 2GB of RAM and SATA discs (7200 RPM). So, your typical entry level server. In fact, maybe now it might be lower than entry level.......
When you deploy your web mapping application, you want it to run as fast as possible. There are a number of "tricks" you can use to make it even faster. Many of these tricks seem to be missed when people deploy websites (GIS based or otherwise).
HTTP compression. This can really shrink the size of your HTML, Javascript or CSS files. usually to about 20% of what they were originally. With GIS Mapping sites, there is usually quite a bit of logic going into the JavaScript end - so making your JavaScript files as small as possible is a real benefit. For example - iws.js - one of the main JavaScript files went from 140KB to just 29KB!
Minification of JavaScripts, CSS and HTML. Minification indicate the removal of excess or unnecessary whitespace or comments in your JavaScript or CSS files. Cutting out this space can reduce the size of a text based file by around 30%. With this size, I also strip out excess whitespace in the HTML files.
Minification often extends to renaming variables in JavaScript files to "shorter names", saving on size of data. I have had mixed success with this - sometimes it seems to create errors in my code.
Combine CSS and Javascript files. Reducing the number of individual requests for files speeds up data access. So, where possible I have grouped CSS and Javascript into one larger file, rather than separate files. Each file request can take up to 200 miliseconds. So, if you have 10 or more external scripts, it can quickly add to your total loading time.
Settings a long expires header on resources that don't change often. This means that a browser doesn't have to keep requesting the same resources over and over again - even if it is just to find out the resource hasn't changed. I have set a long expires on my icon images, as well as base JavaScripts, CSS files.
R....
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