Fetching all of the AHN2 raster data with FME.

AHN2

Recently the AHN2 dataset was released to the public via the Dutch SDI (PDOK)

This was a perfect opportunity to set FME to work on this newly available resource.

This time the rasters and point cloud data was made available via an Atom feed XML.

This means that you can download the 5 meter GeoTIFF rasters and LAZ point cloud data on a national scale. 

Well I had to try that...just for a starters, to see how long it would take me to build the workspace and download the raster data.

Workspace

Building the workspace took about 5 minutes, the tricky part was to make sure you are grabbing the correct part of the XML, after that it's a walk in the park, letting FME get the data off the Internet. 

The workspace itself (4 transformers) starts with a Creator to jump start the HTTPFeatcher, that grabs the XML document.(AtomFeed)

After finding the correct XML tag and extracting the information (URL) with an XMLFragmenter the string is passed to retrieve the rasters (RasterReader).

Data

The raster data took a while longer to download but that is mainly due to the fact that the rasters need to be fetched off the Internet.

Another aspect that I wanted to test was the ability to save the data, so I made use of the (very much welcomed back!!) capability to save the data directly from the Data Inspector.

The FFS is the native FME format, which supports vectors and rasters. The ability to compress the data was applied to see how compact such a big dataset can be made.

After about 15 minutes the Data Inspector happily reported finishing the job of saving the data, I was pleasantly surprised to find out that only about 6 gigabyte of space was necessary.

Results and development

 After downloading the data, I wanted to make the workspace easy use to use and flexible for any spatial selection (My guess is that not many people are interested in the all dataset, but mainly the data in a specific area of interest)

AHN2 raster data.

So what can be better than combining additional services containing rasters bounding boxes and boundaries.
That way you can select your area of interest be it a municipality border or a selected area of interest.

The Dutch SDI provides the possibility to download data in much the same way, but once you have the data in your FME workbench, you can do much more that just download.

This is actually where it starts to get interesting, the opportunities that the height data provides are numerous.

More about downloading the point cloud data and combining the different SDI services on the next post.

By the way did I mention the the rasters are read from a zip file? Well no because that is so 2013 ;) 

Fetching all BAG WFS features

Fetch boy fetch!

 

 

 

 

 

Origin 

The idea for this post originates from a tweet by a FME user on a blog post in which information is given about accessing the Dutch SDI (PDOK) OGC webservices. For original post (in dutch) see brentjesgeoict.

Curiosity

In the post a number of handy tips are given concerning fetching all features residing in the national registration for addresses and buildings service (BAG)
I must admit that until now I have used OGC services strictly as input data source without actually realizing that there might be a limitation. After getting curious about it I started finding out more about the possibilities of smart usage of OGC services and the ability to make the use easy via FME.

 OGC

I am not going to give you a detailed overview about OGC, for that use the Internet, but I will mention the fact that the OGC standards are unique in the GeoSpatial sector for being widely accepted as created standards (in contrary to the de facto standards e.i. shapefile)

Making it easy

The recommended way to overcome the service restrictions (for this case there is a restriction on the service that results in a maximum of 15000 features returned) is to make use of the count and startIndex parameters of the GetFeature request.(WFS 2.0.0)
To make sure that all of the features are returned, an initial query ("resulttype=hits") returns the total number of features served.
With that a simple calculation can be done that ensures the correct number of requests are always sent.
The use of parameters in the workbench makes it easy to adapt the GetFeature request syntax to any available feature type.
Allowing the area of interest to be selected (municipality, province or national) at runtime and the calculated requests make it all care free and really easy to use.

FME Workbench

Results

To make the results accessible I have created a Google map.
With the help of the filter option simple questions such as: "all the buildings built last year?"* can be directly answered and visualized.






* Results are based on a temporary service, and may not be updated or complete.
Interested in the workspace, give me a call. 

FME 2013 in retrospect.

FME 2014 release.

Now with FME 2014 available, it is for me a time to reflect back on the changes made in the 2013 release.

Thinking back on the adaptations made for FME 2013, especially the ones that I have used the most, I can truly say which are my favorites.

1. Conditional processing FME 2013 SP1.

Original FME Evangelist post

Funny enough my first question on the FME Community was about such conditional processing.
At the time it was only possible to achieve it with multiple transformers, testing and setting/mapping values (or an elaborate sql statement)
With the introduction of conditional processing, the amount of transformers for such processing was reduced to 1 e.i. the AttributeCretor.
The AttributeCretor has been replacing more and more transformers on the canvas, mainly testing and mapping transformers obviously.

2.  Data Inspector FME 2013 SP1.

Right from the start of 2013 I have been using the Data Inspector instead of the Universal Viewer.
Since viewing the data in question, is such an essential part of the process of transformation, it's obvious that a capable tool for the job is needed.

The Data Inspector for me is such a tool, especially since it did not only replaced the Universal Viewer, but outdated it too. The addition of the table view to the Data Inspector, did turn out to be a very useful addition that added a certain maturity to the all concept of data visualization within FME.

The last Universal Viewer remnant, that I was missing, is now also been made available in the new FME 2014 release. Saving from the Inspector is now possible in two ways, saving all the features, or just the ones viewed.

3.  New Excel reader/writer FME 2013 SP2.

Blog post

Several posts have been published in the past year about the new Excel reader and writer. It is truly an major improvement to the old reader/writer, supporting formulas, colors and a wider range of data types (XYZ coordinates to geometry), just to mention a few.

Surprisingly the new reader does not support a where clause, as the old reader did, I am still puzzled about this, especially since Excel is treated as a database. Possibly the underlying technology change is the cause of this reader parameter missing in the new reader.

The handling of multiple schema, especially originating from multiple feature types, is still an unresolved issue. Even then the advantages of the new Excel reader/writer capabilities greatly outweigh these few introduced glitches.



So there you have it, these are my favorite and most used FME 2013 improvements I wanted to share.
Now with that out of the way I can send more time on FME 2014 in future posts exploring the sea of opportunities.

Have a feeling the it will all be about nothing.....

FME 2014 - look and feel

FME 2014 is released and available. I have only been using it for the past week, this post will be about my first impressions of the new release.

My first impression of FME 2014 is the amazing speed in which the new look makes  FME 2013 look so chunky and outdated.
This might not be (and probably isn't) the most important addition in the new release, but its a striking one, right from the start.
Its is very easy to get used to the smoothness introduced with this new FME release.

Again hat's off for the people at Safe!!

A few more apparent improvements\changes are:

• Bookmarks and annotations have had a major touch up which makes them more user friendly and easier to use, supporting links and adjustable text properties.

•  Naturally a new theme is also expected with every release of FME, as announced the lizard came back to vanquished the zipster into the sands of the red planet.

• Another immediately apparent change to me, is the option to save your workspace while the translation is running. This is for me a major user interface improvement, that can save a lot of awkward moments when running unsaved workspaces crash.

• The selection of features on the workbench canvas is another major improvement, don't forget to activate it! (Tools > FME Options >Workbench)

Well thats it for now,  as I continue to use FME 2014 and get better acquainted with all the new additions, I  expect additional posts about FME 2014 additions.

XML the xfMap path

Most of the people I meet in the Geo-information sector are aware of FME as a translation tool  from one format to another.

That is originally what FME was built for (20 years ago) and is still one of the jobs where FME transcend all the rest of the available tools.

But FME is much more than a format translation tool, is as good as any GIS software available , and in my opinion it blows away most of them.


I constantly get amazed looks from costumers, when explaining them that most of their requirements can be done with FME, and in most cases in a single workspace.

The ability to dazzle with FME is not restricted to the spatial domain, FME's support of non spatial formats (for example the Excel writer, the shapefile of non spatial) makes it possible for non spatial people to benefit from FME when a serious user is around.

XML is another format where FME can be of great benefit, since almost any imaginable operation on XML can be done in FME, the combination of spatial and non spatial makes FME a truly versatile tool.

Since nowadays you can find XML almost everywhere, from OGC services styling to cadaster data sources all is served via XML.
The only main difference in the data is the schema (data model) and that can range from simple to extremely complex.

In FME the advised way of approaching XML data is by using feature paths, this makes XML handling very easy and does not require any in depth knowledge of the data schema.
However in some cases using feature path doesn't (and sometimes can't) handle the XML as good as xfMap.
xfMaps are the basis of XML handling in FME and if you know your xfMap then handling XML becomes super easy. The main drawback is that you do need in depth knowledge of the data schema.

The big advantage of using  xfMap over feature paths is the ability to read very large XML files, I suspect that when using feature paths the file is read into the computers memory, this can be an issue when dealing with huge volumes of data, even if your machine is supercharged and all of your FME settings are in place.

When using xfMap the file that crashed your machine trying to handle it with feature paths, will now easily load the same data.

I have tested this with the new BRK (new cadastral registration) data, available from the Dutch Kadaster.
Trying to parse the XML (260MB) with feature paths, just crashed my machine (and I do have a reasonable machine with the FME settings set properly).
With a very simple (and powerful) xfMap the same file loaded within 10 seconds and was ready to be transformed.

So to wrap it up, use xfMap if:

1. The data volume is large and the feature paths configuration doesn't comply.
2. The data schema is static
3. You have too much time on your hands.

This is the last post for 2013, if you have already had some glimpses of what is to be expected for us with FME 2014, then I am sure you are as excited as I am!

A prosperous 2014 to us all.

Itay

Bye Bye Universal Viewer

What is the first thing they teach you in a FME course? To have a look at the data !

All the way back to my first careful steps with FME, the Universal Viewer was there to help visualize and query the data I was working with.

A great tool and without it, it would have been unthinkable to work with any type of data.

 FME Universal Viewer

Since the first appearance of the next generation viewing application of FME (Data Inspector), I have been hesitant to make the transition from the known and familiar Universal Viewer to the new Data Inspector.

Sure there have been moments when I thought OK now I am finally going over to the Inspector, I mean its fancy and you can view in 3D (That was back in the days when the 3D was hot). But somehow I never got around to finally take the final step.

???

Since FME 2013 was released I have been only using the Data Inspector (I remember somewhere in the beginning of 2013 that the FME Evangelist himself made the transition and naturally recommended it to us all).
Throughout 2013 a number of features have been added to the Data Inspector (background maps, table view) that made the Universal Viewer really seem old fashioned.
The only Universal Viewer functionality I still miss in the Data Inspector is the ability to save the viewed features.

So bye bye good old Universal Viewer I suspect I wont see much of you anymore (wasn't FME 2013 also the last release with the Universal Viewer?)

And for those of you that still cling to the Universal Viewer, take the final step it's worth it!

It's something unpredictable, but in the end is right, I hope you had the time of your life.
- Green Day

Rotten Apple

As an ETL specialist you are mostly involved in moving data, doesn't matter what you do with the data you are always moving it in some way.

There is always a starting point (E) and an end point (L) to the transformation (T), this time I would like to share some of my experience concerning the ETL process.

This will no be so much about how to do this or that, but more about the delicate and sometime awkward situations that can arise in the process.

 If you are doing custom transformation work or it is just part of your daily work, the hardest part of the ETL process can sometimes be the process around the technicality of it.

Since you are responsible for the 'black box' for most people (and managers especially) you are bound to get the blame if it goes wrong.

 Lesson 1: make it clear from the start what your responsibilities are!

Make sure that the parameters and expected results of your job are well defined before you even open FME!

This can take some time and you will be seen as a pain in the .... but it can save you a lot of pain and it will make your goals clear and well defined.

In most cases involving large and complicated database schema and design, you are dependent on others to provide you an insight about the database schema or even better: queries to preform on the database.

Most of the times you get a reaction like: " I thought you are the ETL specialist...." or " Don't you know how to do it yourself?", sounds familiar?

Lesson 2: clearly define the input and expected results (especially if large and complicated database schema is involved)

OK you got over the first hurdles and created your workspace and it works or at least you think it does, but wait a minute after some time it turns out that it is not providing the expected results (oops embarrassing moment) but hey we are all human and we make mistakes.

So you rack your brain trying to find where the mistake is done. Eventually you find no fault in your work and the workspace does what it is suppose to do.

In fact you have delivered what was possible based on the information you got, the problem arises when you are not supplied the correct information.

Lesson 3: document the defined input, expected results, responsibilities and ETL process.

Despite it all it can always go bad, there is always a rotten apple.....somewhere in between it all.