Skip to main content

Elaborate Hack for Transparency

ArcGIS supports transparency*.
* Some restrictions apply.

But if you really want to do anything with transparency you quickly learn that the functionality available is completely inadequate.

I work with a number of layers that rather than resembling a stain glass window with neatly segmented regions, come closer to resembling the outcome of tossing said window down a flight of stairs. The smashed bits all laying in a pile overlapping each other sometimes seven or eight layers deep.

But how to represent this mess? In ArcGIS you really can't because ArcGIS only draws the top most layer. Take a yellow piece of stained glass and drop it on top of a blue one and in the overlap you don't get green, but blue. Even when you set transparency!

The only way to complete our Glad bag analogy is to make two independent layers with transparency applied. Not bad when there's only two. But what if there's 582? That would take a while. And what if the layer with 582 is constantly growing so we'd have to make new definition queries or static shapefiles every single time we appended a record. Not doable.

However while ArcGIS does not support transparency properly, it occurred to me that ArcIMS does.

With that idea, I present:

Hacking ArcGIS - Lesson 1: True Transparency


Step 1: Author a new map .AXL in which includes transparency (0.6 works well) and displays by unique value.
NOTE: I don't use Author at all in more, but it works great for building a unique values display.


Step 2: In ArcIMS Administrator create a new image service using the .AXL

Step 3: Add the new image service to your ArcGIS map.

Step 4: Use a copy of the layer with display set to transparent to label.

That's it! You can now print and export a map with true transparency.

Comments

Popular posts from this blog

Attachment Reminder - and more for MS Outlook

I just did it again. We don't like to admit it, but we all have. You write a long letter describing the attachment, press send and then 10 seconds later remember you didn't actually attach the message. I finally decided to do something about it. Turns out it isn't too hard. Chiefly because Jimmy Peña at Code for Excel and Outlook already did all the hard work of writing up an excellent MS Outlook Etiquette Check Macro that does all the dirty work for you. What's left for you to do? In MS Outlook go to Tools > Macros > Visual Basic Editor Under the Project Panel (far left) Browse to Project1 > Microsoft Office Outlook Objects > ThisOutlookSession Double-click ThisOutlookSesson to Open (if you haven't been here before this will be a big blank canvas) Visit Code for Excel and Outlook Etiquette Check Code and select "Copy to Clipboard" at the top of the code. Or you can also copy from the code I've modified below if you prefer.

Auto Format (and Color) Outlook Appointments

A few years ago I got turned on to the idea of indexing your life by color. In a quick glance your mind can comprehend really complex patterns. By coloring entries in my calendar I am able to tell immediately if I am available or if a future appointment conflicts with a work meeting. There are a number of ways to set this up. Outlook allows you to add a label to every appointment. However this is an Outlook specific feature and I sync my calendar across Outlook, Yahoo! and iCalendar. The later two don't even have labels. Besides, calendars should be simple. Complexity only hinders usability, so I prefer an automated solution. How to color appointments in Outlook automatically: In Calendar, right-click the calendar grid, and then click Automatic Formatting on the shortcut menu. Click Add, and then type a name for the rule. In the Label list, click a color. Click Condition to specify the conditions under which the color will be applied. Note: If you manually assign a color to a

Simple HTTP Redirect with Querystring in IIS7

HTTP Redirect seems simple enough. Always was in IIS6 and in IIS7 there's even a button labeled HTTP Redirect that promises relative redirects.  It looks like it'll be as easy Apache finally.  That is until you try to redirect a querystring.  Then everything bombs. Turns out it still is relatively easy, except you have to know that Microsoft changed $S$Q to $V$Q. Why? $Ss and $Gs I suspect. And How. In our example we'll redirect all pages under http://olddomain.com/content to http://mydomain.com/content. Pick the virtual directory you want to redirect. e.g. http://olddomain.com/content Click HTTP Redirect under IIS in the IIS management console. In the HTTP Redirect Dialog: Check Redirect requests to this destination Enter your new path ending with $V$Q.  e.g. http://mydomain.com$V$Q Counter-intuitively check Redirect all request to exact destination (instead of relative destination) Choose the appropriate Status Code (Permanent or Temporary)