General

What is a dataset layer?

A dataset layer is a set of observations made in surveys conducted by one of the OBIS-SEAMAP data providers. It can contain observations of multiple species from multiple surveys. Dataset layers have one-to-one relationship to those appeared in Datasets page.

What is a species layer?

A species layer is a set of observations of the specified species across all the datasets OBIS-SEAMAP holds. As there can be more than one dataset involved, the survey methods vary.

I got "session invalid or has expired." error. What does this mean?

To serve all users better, the Online Mapper has session management implemented. When you get started with the Mapper, your session starts. Your session expires when you are off for about 20 minutes (to be precise, it's 1,440 seconds). Then the Mapper logs you out and shows you that message when you return.
While you are operating the Mapper, your session continues.

Dataset Layer

How can I map dataset layers?

There are a couple of ways to map dataset layers.
<< From Datasets page >>
Find the dataset you are interested in in Datasets page.
Click on the thumbnail map under 'map' column. You'll see several mapping options.
Click 'Online map' link.


<< From 'Dataset detail' page >>
Click 'Map Online' link in 'information & action' box in the left pane of the page.

<< From Online Mapper>>
Navigate 'Add'-'Add dataset'.
You'll see selection page similar to 'Datasets' page.
Make use of search features as needed to narrow down the list.
Follow the same steps described above or simply click the plus sign to add it to the online map.

Species Layer

How can I map species layers?

There are a couple of ways to map species layers.

<< From Species List page >>
Find the species you are interested in in Species List page.
Click 'Online map' link in 'map' column.

<< From Species Profile page >>
Click 'Map Online' link in 'information & action' box in the left pane of the page.

<< From Online Mapper >>
Navigate 'Add'-'Add species'.
In 'Search and Add Species to Map' popup window, enter the species scientific or common name. This window is equipped with 'as-you-type search' functionality. As you type in your species name, the candidate species are listed below. If you find your species while typing, you can click on the species name in the list instead of keeping on typing.

Once you finish typing or select the species from 'as-you-type' results, click 'Add '.

How can I map observations of a certain species at a higher taxonomic level (e.g. genus, family) than species and what do I get?

The same steps as above apply. Just type the scientific name or common name, if any, of the species.
For example, if you are interested in beaked whales at genus level, type 'beaked whales' in 'As-you-type search' box. You'll see the result list including Mesoplodon, which is the scientific name of the genus beaked whales.

Select it and click 'Add'.

The resulting observations include not only those identified as Mesoplodon (the observer didn't identify it at species level) but also observations for the taxonomic children (e.g. M. bidens, M. bowdoini etc.).

When I map a species at genus or higher taxonomic level, the map should include observations for the taxonomic children. But the points are classified by dataset. Can I change the legend by species (taxonomic children)?

Yes, you can change the classification from by dataset to by species.
Navigate 'Tools'-'Items in layers'.
In the popup window that appeared, choose 'species' from 'Colored by' options.

Click 'Apply'.

Navigation Tools

How can I find whose dataset a specific point comes from?

When you map observations of a species or observations from multiple datasets, you can't easily tell which point comes from which dataset.
The Identify Feature tool helps you find the dataset from which the point comes. With Identify Feature, get the point data in Query Results popup. You'll find the column named "_dataset". The value in the column is clickable and leads you to the Dataset Detail page from which the point comes from.

How can I find what species a specific point is?

When you map observations of a dataset that includes observations of so many species that the legend is hot helpful so much, you can't easily tell what species a specific point represents.
The Identify Feature tool helps you find the species the point represents. With Identify Feature, get the point data in Query Results popup. You'll find the column named "_sp_scientific" and "_sp_common" . These are the species scientific name and common name, respectively. The scientific name is clickable and leads you to the Species Profile page for the species.

Projection

What's the difference between "Pacific centric" and "Greenwich centric"?

A greenwich centric map has its central meridian at zero degree (Greenwich) and its projection is based on geographic coordinate system (EPSG:4326). This map is suitable for most of the data OBIS-SEAMAP provides except those having pacific-wide extent. It may also be needed when you overlay wms layers with geographic coordinate system, which is very common.
A pacific centric map has its central meridian at 180 degree (the international dateline) and its projection is based on Gall stereographic. This map is good at showing data expanding pacific. Most of the data from OBIS-SEAMAP can be displayed properly. However, some polygon layers and wms layers whose spatial reference is EPSG 4326 may not be well projected.
Please note when you switch from the one to the other, the existing layers are reset.

Why do I see some lines strangely expanding in some datasets? It seems they go around the globe taking a longer path than a shorter path.

This is a problem related to the line extent and the map projection. When a line crosses the international date line, MapServer can't handle it properly with the default projection (geographic). If this is the case, please change the projection to, say, Asia Lambert.
Alternatively you can make the map pacific-centric. To do so, just click "Pacific centric". Please note when you switch from the one to the other, the existing layers are reset.

Geographic	Asia Lambert
mi
Pacific centric map (Gall stereographic)

Miscellaneous

I expected that a dataset layer and species layer can be shown in the same map. But 'Online map' link always opens another window while there is already a map window. I use Firefox 1.5.

In general, dataset layers and species layers can be mapped in the same map. We found an exception that when the user uses a tabbed browser such as Firefox and forces it to open a new tab whenever the link tries to open a new window, 'Online map' opens another tab if the layer the user have added is a different type from the one in the existing map.
To work around this in Firefox, turn off "Force links that open new windows to open in:".