Polar Mapping Prototyping and the Lessons Learnt

Shinobu KawahitoRemote Sensing Technology Center of Japan (RESTEC)in support of Japan Aerospace Exploration Agency (JAXA)

WGISS-28 Pretoria

Overview of the Prototype

• OGC/WMS and other related standards based web mapping

system• Interactive with distributed WMS servers • Serve images in polar specific projections

System Features

User Friendly

• The image applied in this prototype focuses on “temperature”(to show Snow extent, Sea ice extent, etc)

Mapping Theme

• Easy to compare multiple images • Easy to view time dependent variations and to select a date of

interest

System Designing User Friendly GUI design

(Requirements) • Multiple images be compared easily

(Solution) • Adjustable image transparency was introduced.

Each of multiple images is sent independently for GUI (not combined

beforehand to one image) thereby allowing the GUI to change their

respective transparency to answer the needs on the spot.

(Requirements) • Time sequential changes be shown easily and a date of interest be

specified on the spot.

(Solution)• Added an indicator to “Date Control” for this purpose.

Snapshot

Snapshot

Create One Final Overlaid Image

Role of Tiers in producing an Overlaid Image

GUI WMS Client WMS Servers

AMSRImage (IC)

Others

Transparency fot the three middle images is variable.

＋

＋

＋

Maps＋

Overlay in WMS Client

AMSRImage (SWE)

AMSRImage (SST)

AMSRImage (IC)

Others

Maps

AMSRImage (SWE)

AMSRImage (SST)

Create Five Independent Images

Overlay in GUI

Top Layer（ Vector Maps ）with transparent background

2nd Layer（ Daily AMSR-E IC ）with transparent background

3rd Layer(Daily AMSR-E SWE)with transparent background

4th Layer(Daily AMSR-E SST)with transparent background

5th Layer(Other Images)

Overlaid Image

Overlay in GUI - Five Map Layers and Data Categories

Findings and Lessons Learnt

• WMS servers which support OGC/SLD will change styles

(width, color, symbol, etc) of features (points, lines, etc)

dynamically answering user’s requests. Images from different

resources can be harmonized by utilizing this ability.

Better Portrayal with WMS + SLD

Original image provided by an NSIDC server

Changes made on some features to follow SLD requests

Findings and Lessons Learnt (cont’)

• Evolved Web browsers and RIA allow various system

configurations for performing interactive mapping and portrayal. - The portrayal includes : overlay images, draw lines, place marks,

draw graphs ..- The tier to perform portrayal:

▪ Server-sides are capable of complicated portrayal, but not so

responsive to interactive manipulations as they should be.▪ GUI-sides provides a quick response once the required data are

ingested, but may spend more time in retrieving the data.

In which tier the portrayal be made

• Projection conversion is a merit of WMS, but it may collapse

some of the appearances; strings labeled to images in

particular.

Images containing a label

Findings and Lessons Learnt (cont’)

• For time-series dataset such as AMSR-E daily data, a problem arises to decide

which names shall be applied to <Layer>; dataset name or name of each data? - When dataset name is applied, GetMap requests will have a difficulty in

identifying each of the data (such as partial scenes) unless vendor-specific

parameters are used additionally.- When data name is applied, all the information must reside in a single

document, which is not practical when a large number of data are applied in

WMS servers.• In our prototype, AMSR-E IC (SWE, SST) has only one image per day. So, we

have assigned dataset name to <Layer>, while Time parameter is used to

identify each of the daily images in issuing/parsing a GetMap request.

• Further, each <Layer> can contain items such as <MetadataURL>,

<DataURL> which help in describing data and accessing real data. Dataset

level or data level of these items should be consistent with the level of <Layer>.

“Capabilities Document” ( = WMS/GetCapabilities response in XML)