Canadian Database of Geochemical Surveys

Index Map Help Topics

Overview

The index map shows the geographic extent of surveys in the geochemical database. "Selected" surveys are shown as green polygons, and "highlighted" surveys as red polygons. Highlighted surveys will always be a subset of the selected surveys. To select surveys based on selection criteria, use the form on the left side of the page (see Form section below). To highlight surveys, use the query tool (i) above the map (see Map section below). Once the surveys are highlighted, they are listed in a table below the form fields below the index map. Note that when the index map is initially displayed, every survey (over 1200) is selected, but none are highlighted. A description of how to refine the number of surveys that are selected and how to highlight them follows:

The Index Map Query page is divided into three main sections: Form, Map and Results.

Form: The Form section is found on the left side of the page. This section contains several form fields that allow the user to refine the selected surveys based on various selection criteria. Beneath these form fields is a "key map" of Canada, which shows where the main map is located. ( left section detailsmore… )
Map: The Map section is found on the right side of the page. This section contains the main map, showing the selected and highlighted surveys. There are several map navigation controls above the map, including the query tool (i) used to highlight surveys. Below the map there are several form fields which can also be used to navigate the map and alter its appearance. ( right section detailsmore… )
Results: The Results section is found at the bottom of the page. This section lists the surveys that have been highlighted by the user. Within this table there are hyperlinks to more detailed information. ( bottom section detailsmore… )

In the top right corner of the Index Map Query page are three green buttons. The "Map" button allows the user to skip directly to the map. When the map has "focus", keyboard shortcuts can be used to pan and zoom (see Instructions for Keyboard Users keyboard help section below ). The "Results" button allows the user to skip to the table of highlighted surveys below the map. Again, the keyboard can be used to navigate around the table. The "CDoGS" button takes the user to the home page for the website.

Description of Form Section

The Form section on the left side of the Index Map Query page allows the user to choose different criteria to select surveys of interest. The Limit Selection button below the Form section must be clicked before the selection criteria are applied to the map. The Form section contains the following fields:

Survey Count

The survey count represents the number of surveys that are currently selected (green polygons). When the index map is first displayed, the survey count corresponds to the total number of surveys in the catalogue (1305 in March 2015). The value in the box cannot be changed by the user. The survey count will change as surveys are selected based on user-specified criteria.

Province

A drop-down list allows the user to select a province or territory of interest, to constrain the selected surveys. For example, picking Nunavut will limit the selected surveys to those that lie wholly or partly in Nunavut. When the default value "All" is selected, surveys in all provinces and territories are displayed.

Organisation

A drop-down list allows the user to select an organisation to constrain the selected surveys. The organisation associated with each survey is generally the one that was responsible for the original sample collection. The Geological Survey of Canada is broken down into several organisations that correspond to the present-day GSC Divisions. When the default value "All" is selected, surveys carried out by all organisations are displayed. The "Unassigned" category in this list represents work carried out by contractors or universities, for example. In this case, the person carrying out the work is not associated with one of the geological organisations in the list.

Survey Type

A drop-down list allows the user to select a "survey type" to find surveys of interest. Each survey is assigned to one or more survey types, which generally reflect the type of sample material that was collected (e.g. till) but may also be based on other criteria (e.g. indicator minerals). Using the drop-down list, it is possible to select only those surveys where vegetation was collected, for example. Although a survey may be assigned to more than one survey type, only one type may be selected at a time. The exception is the default value "All". When "All" is selected, surveys that collected any of the sample material types in the list are displayed.

Year

The year field is a combination of two drop-down lists that allow the user to select surveys based on the year of sample collection (or the first year of collection if samples were collected over more than one year). The first drop-down list allows the user to choose the "operator" for the selection query - either "equals", "less than", "less than or equals", "greater than" or "greater than or equals". The year of interest for the selection query can be chosen from the second drop-down list. The default values are "=" and "All" so that surveys carried out in all years are displayed.

Title

The title box allows the user to search for a text string that may occur in the survey title. The search is case-insensitive. The survey title is the short descriptor for each survey, as presented in the Surveys index table.

Abstract

The abstract box allows the user to search for a text string that may occur in the survey abstract. The search is case-insensitive. The abstract briefly summarises the survey in a few hundred words and appears in the Survey Description section of each survey's Survey Metadata page. (e.g. svy050007).

Location

Three input boxes allow the user to select surveys based on geographic location - specified as either a single latitude/longitude point or an NTS sheet:

latitude/longitude: Enter the latitude and longitude as decimal degrees, remembering that longitudes in the western hemisphere are negative. Latitude must lie between 42 and 90. Longitude must lie between -142 and -50. When the map is redrawn, it will be centred over the specified point.
NTS sheet: The NTS sheet can be specified in either 250K format or 50K format. KML index maps are available from the CDoGS home page for both 250K and 50K sheets. Map sheets should be specified using the standard NTS sheet identifiers, e.g. 41P for 250K; either 41P5 or 41P/5 for 50K. When the map is redrawn, it will be centred over the specified NTS sheet.

Raw Data surveys only

Toggling this checkbox on will limit the results of the search to those surveys for which raw data have been loaded into the database and therefore are available in a standardised format as MS-Excel® spreadsheets and KML files that can be viewed in Google Earth™.

Limit selection

Clicking this button will execute a search of the database according to the criteria selected by the user in the form fields. The map will be redrawn with the selected surveys shown in green. Any previously highlighted surveys (shown in red) that are in the new set of selected surveys will remain highlighted. The number of selected surveys will be given in the "Survey Count" field.

Reset

Clicking this button will reset all of the form fields, and the map will revert to its initial state, with every survey selected, and none highlighted.

Key map

Below all of the form fields, a small map of Canada is displayed, which outlines the part of Canada that is currently being displayed in the main map on the right side of the page.

Description of Map Section

The Map section on the right side of the Index Map Query page allows the user to search the Canadian Database of Geochemical Surveys (CDoGS) for surveys of interest, refine the search using selection criteria and change the display of the map. The Map section has three distinct parts that will be described separately: Navigation, Main Map and Map Display Fields.

Navigation Section

The Navigation section is located at the top of the Map section, above the main map. There are two sets of navigation buttons in this section. One set is intended for map navigation using a mouse, and the other set is intended for map navigation using a keyboard and these are described separately below.

Mouse Navigation

There are five tools that allow the user to navigate the main map using the mouse. These five tools control the map display and survey highlighting functions, allowing the user to zoom, pan and query. To activate the tool, click on the icon representing the tool. From left to right, a description of the function of the five tools follows:

Zoom In

When the Zoom In mode is active, the mouse can be used to "zoom in" to an area of interest on the map. If a point on the map is clicked, the map will be redrawn at a more detailed scale, centred on the point the user clicked. Alternatively, the user can hold the mouse button down to draw a rectangle on the map. Releasing the mouse button will cause the map to zoom in to the area defined by the rectangle. If the mouse is moved off the map while the mouse button is pressed down, the zoom operation is cancelled. This is useful if the user realizes that the zoom rectangle is in the wrong spot or is too small. The map will not be redrawn in the unwanted area, saving time. Any highlighted surveys will still be shown in red, as long as the zoomed in area still covers the area that contains the survey.

The user can also zoom in to a specified box or point by entering values in the form fields below the map (described right lower section below ).

Zoom Out

When the Zoom Out mode is active, the mouse can be used to "zoom out" of the current view to see more of the map. When a point on the map is clicked, the map will be redrawn at a less detailed scale, centred on the point the user clicked. Any highlighted surveys will still be shown in red after the zoomed out view is displayed.

The user can also zoom out to a specified box or point by entering values in the form fields below the map (described right lower section below ).

Pan

When the Pan mode is active, clicking on a point on the map will redraw the map at the same scale, centred on the point where the user clicked. This allows another part of the map to be displayed, but at the current scale. Highlighted surveys will still be coloured in red, but may not be visible depending on where the user clicked.

The user can also pan to a specified box or point by entering values in the form fields below the map (described right lower section below ).

Zoom Out to Full Extent

As soon as this tool is clicked, the map is redrawn to show the entire map of Canada. Any surveys that have been highlighted are still shown in red after the map is redrawn.

Query

When the Query mode is active, surveys of interest can be highlighted and more information about them will be provided. Highlighted surveys will be drawn as red polygons, and will be listed in a table in the Query Results section near the bottom of the page. For an explanation of the contents of the table, see bottom section below ).

Using a mouse, surveys can be selected for highlighting either by clicking on a green survey box on the map, or by drawing a rectangle around as many surveys as the user chooses. Once the survey is selected by clicking or drawing a rectangle, the highlighted surveys are shown in red and the highlighted survey count is shown at the top of the Results table. If survey areas (green boxes) overlap, clicking on one survey will also highlight all of the surveys whose area contains the point that was clicked.

Performance warning: the more surveys that are chosen for highlighting, the longer it will take the Query Results table to display.

A highlighted survey or surveys will be shown in red until the next query using the tool is executed. For example, if the user highlights a survey in Ontario, the map will be displayed with the Ontario survey shown in red. If the user then highlights a survey in Manitoba, the map is redrawn with only the Manitoba survey shown in red. To highlight multiple surveys at once, use the mouse to draw a rectangle around them, as noted above. Once again, the next multiple survey selection will then only show the latest highlighted surveys in red.

Keyboard Navigation

There are eight tools that allow the user to navigate the main map using the keyboard. These eight tools control the map display and survey highlighting functions, allowing the user to zoom, pan and query. To activate the tool, use the "Tab" key to tab to the icon representing the tool, then hit the "Enter" key (note: using SHFT-Tab tabs in the opposite direction). From left to right, a description of the function of the eight tools follows:

Zoom In

Hitting the "Enter" key zooms in on the centre of the map.

Zoom Out

Hitting the "Enter" key zooms out on the centre of the map.

Pan Left

Hitting the "Enter" key pans the map to the left.

Pan Right

Hitting the "Enter" key pans the map to the right.

Pan Up

Hitting the "Enter" key pans the map up.

Pan Down

Hitting the "Enter" key pans the map down.

Zoom Out to Full Extent

Hitting the "Enter" key immediately redraws the map, to show the entire map of Canada.

Submit

Hitting the "Enter" key submits a request to highlight all of the surveys currently shown on the map and query them. Highlighted surveys are drawn as red polygons, and will be listed in the Results table in the Query Results section near the bottom of the page. Using the keyboard, it is not possible to highlight just one survey or a group of surveys.

Performance warning: because the Submit button highlights and displays every survey currently shown on the map, the Query Results table may take a few moments to display.

Main Map Section

The main map is located in the middle of the Map section, below the map navigation buttons. When the Index Map Query page is first opened, this section of the page displays a map of Canada showing all of the surveys catalogued in the database. Selected surveys are shown in green and all of the surveys are selected when the page is first opened. Highlighted surveys are shown in red. Survey selection can be refined by entering criteria in the form fields to the left of the map (see left section above ). Highlighted surveys are a subset of selected surveys, and are highlighted by using the "Query" icon in the mouse navigation section Mouse Navigation section , or by using the "Submit" icon in the keyboard navigation section Keyboard Navigation section .

Keyboard shortcuts can be used to zoom and pan the map if the map is active, or has "focus". You can give "focus" to the map either by clicking the mouse within it, tabbing to it, or using the "Map" button at the top of the page. Clicking the mouse or using the "Map" button is faster than tabbing to the main map. The keyboard shortcuts are enabled by using the four arrow keys (to pan up, down, left and right), the "+" key (to zoom in) and the "-" key (to zoom out). There is no keyboard shortcut to query the map.

The map is drawn using a Lambert conformal conic projection, with standard parallels at 49 and 77 degrees north, and a central meridian at 95 degrees west. Lines of constant longitude are straight and converge at the north pole. The central meridian is oriented vertically. Lines of constant latitude are circles, centred on the north pole. Scale is true along each of the two standard parallels.

The form fields below the map report the extent (in degrees), the scale and the width (in km) of the displayed map. All of these values are imprecise, because of the effects of the map projection. The imprecision decreases as the map is zoomed in.

The map scale is calculated on the assumption that the image is displayed at a resolution of 72 dots per inch (dpi), and that the image size is either 400x400 pixels (a low resolution) or 1200x900 pixels (a higher resolution). Without knowing the actual pixel size of the user's monitor and whether or not a 400x400 pixel image is actually taking up 400x400 pixels on the user's screen, the calculated scale can only be an approximation. The map scale will only be accurate if a low resolution image measures 5.5x5.5 inches (5.5" x 72 dpi ≈ 400) or a high resolution image measures 16.7x12.5 inches on the screen.

The initial view of the map is at a scale of approximately 1:40,000,000 - a small scale. The scale can be adjusted to a lower limit of 1:5,000 - a large scale that provides more details on the map.

The distance represented by the map width is measured using map projection coordinates, which are metres for the Lambert conformal conic projection used here (but shown in km). The distance will become more accurate at higher zoom levels.

In the Map Limits box, the latitude/longitude extent of the map reports the maximum range for the corners of the map. The most westerly point is in the top left corner of the map. The most easterly point is in the top right corner of the map. The most southerly point will be in either the lower left or lower right corner of the map, depending on whether the central meridian lies to the left or right of the centre of the map. The most northerly point will lie at the top of the central meridian.

Map Display Fields Section

The Map Display Fields are located at the bottom of the Map section, below the main map. This section of the page contains several form fields which allow the user to control the display of the map and they are described below:

NTS

The radio buttons in this form field allow the user to control the base map that is displayed at large scales. As the map is zoomed in, the base map becomes more detailed. At sufficiently large scales (between 1:5,000 and 1:600,000), the base map shown is a topographic map. By default, the base map will be the NTS 250K topographic map for scales between 1:600,000 and 1:100,000, or the NTS 50K topographic map for scales between 1:100,000 and 1:5,000. This default behaviour can be overridden by clicking the 50K button (if the 250K base map is displayed) or the 250K button (if the 50K base map is displayed). This will force the display of the user-selected layer instead of the default layer at all scales between 1:5,000 and 1:600,000 (the topographic base maps are only shown in this range of scales).

For some parts of the country, 50K topographic data are not available. In these areas, the 50K layer will be entirely white. In this situation, the user can force the display of 250K data by selecting the 250K button. To view this behaviour, zoom in to point 55.5N, -75.4W, scale 1:80,000. To do this, enter these values into the Map Limits (leave E and S values blank) and Scale form fields respectively, and then press Redraw. The lower half of the map is white because the 50K sheet is unavailable. Now change the radio button from Default to 250K and press Redraw. The previously white part of the map now displays the 250K sheet.

Map Limits

The boxes in this form field report the values for the bounding box of the displayed map, in decimal degrees. Note that longitudes in the western hemisphere are negative. Also note that as a result of the map projection, these values are inaccurate at small scales.

Values in the boxes can be edited to change what part of the map of Canada is displayed. If just two values are specified (one latitude and one longitude), the map will be redrawn centred at that point. Note that due to the map projection, the map may not be centred exactly around the point. If all four values are specified, the values will form a new bounding box within which the map is displayed. If a point is specified (one latitude, one longitude), the map will be redrawn at the same scale, unless a new value for either the map scale or map width is specified in the Scale form field.

The user can also zoom (in or out) to a specified box or point by entering values in the lat/long input boxes, and then clicking the Redraw button. When the map is drawn, the lat/long fields are filled with the current map extent (in decimal degrees). To zoom to a specific point, simply enter a pair of coordinates for lat/long and leave the other two fields blank (any combination of N/S - E/W is acceptable). To zoom to a smaller area, enter either a N/S or an E/W pair. If all four N/S/E/W values are specified, the map will zoom using the pair of coordinates which produces the most detailed map.

The input boxes will not accept non-numeric characters, except the negative sign (-) for longitude (e.g. -75.4) and the decimal (.) to make decimal degrees.

Once the map display has been changed using the Map Limits or Scale form fields, the display can be reset to the default view of the entire map of Canada with the Zoom Out to Full Extent tool using mouse or keyboard navigation.

Scale

The two boxes in this form field report the current map scale and map width (in km). Either field can be edited to specify a new map scale when the map is redrawn. If both fields are edited, then the map width will be used to redraw the map. If a scale below 5000 is specified, it will be reset by the system to 5000. Similarly, the width must lie between 1 and 5000 km.

The input boxes will not accept non-numeric characters, other than a comma (e.g. 80,000).

To the right of the form fields are three final controls:

Redraw

Clicking on this button forces the map to be redrawn according to the values specified in the NTS, Map Limits and Scale form fields.

Submit

Clicking on this button highlights surveys on the map in red and lists them in the Query Results table located beneath the Map Display form fields. The highlighting is carried out on all of the surveys currently shown on the map when Submit is clicked. If a survey selection had previously been executed using the Form section to the left of the map (e.g. only surveys in Alberta are selected), then only those Alberta surveys are available on the map for highlighting.

Performance warning: the more surveys that are chosen for highlighting, the longer it will take the Query Results table to display.

High res

This checkbox allows the user to select a high resolution map image. The default map image is 400x400 pixels. The higher resolution image is 1200x900 pixels. The higher resolution is useful if the map image is to be saved on the user's computer, but the larger size will result in slower loading of the web page.

Description of Query Results Section

The Query Results section at the bottom of the Index Map Query page consists of a simple table. Each row in the table corresponds to a survey highlighted by the user. The count, or number of highlighted surveys, is given above the table. The query results in the table can be sorted or filtered (help on sorting and filtering is available here).

The following columns are found in the Query Results table:

ID: This column contains a unique number that is assigned to each survey. When the ID associated with each survey is clicked, the survey's metadata page is displayed and it provides detailed information about the survey. A description of the layout and contents of the Survey Metadata Page can be found in the Help topic Surveys. This column can be sorted, but filtering is not very useful.
Grouping: Each survey has been assigned to one or more groups and it appears in this column. The groups are generally based on the sample material collected (e.g. till, soil), but may also be based on other criteria (e.g. indicator minerals). If a survey has been assigned to more than one group, all assigned groups are listed. This column can be sorted or filtered.
Organisation: The links in this column lead the user to the web site of the organisation that was responsible for carrying out the survey. This column can be sorted or filtered.
Year: The year the survey was carried out is given. If the survey spanned several years, the first year is given. This column can be sorted or filtered.
Survey Description: A short description of the survey is provided, which typically summarises what was collected, where it was collected and when it was collected. Although this column can be sorted, it is more useful to reduce the list to surveys of interest by typing a search word into the filter box.
KML: clicking on the icon in this column displays a location map for the survey in a KML viewer such as Google Earth™. Sorting or filtering on this column is not very useful.

Instructions for Keyboard Users

The standard form fields on the Index Map Query page can all be accessed in the normal ways with the keyboard. Map navigation using the keyboard is accomplished in one of two ways:

Keyboard Navigation Buttons: These buttons are grouped together, to the right of the mouse navigation buttons, above the main map. The first six buttons perform standard functions of zooming in, zooming out and panning. The next button forces the map to zoom out to the full extent of Canada. The eighth button will highlight all of the surveys that are currently displayed on the map, and a table listing these surveys will be populated below the map in the Query Results part of the page. The ninth and final button will display this help topic.
Keyboard Shortcuts: When the map is active, or has "focus", the keyboard arrow keys and +/- keys can be used to pan and zoom the map. The map can be given "focus" either by tabbing into it, or by skipping directly to it, using the "Map" button at the top of the page.

Two buttons are provided at the top right of the page, which allow keyboard users to skip ahead to either the main map, or the table of highlighted surveys (in the Query Results section near the bottom of the page). Having skipped ahead to the map, keyboard users can then tab backwards (by using SHFT-Tab) to quickly reach the keyboard navigation buttons. The table of highlighted surveys shares the same capabilities of sorting and filtering as other large tables on the website. Help on navigating and manipulating the table is available on a separate page.

Instructions for Screen Reader Users

Screen reader users will benefit from the keyboard navigation features described keyboard help section above . Additionally, the information that is presented in the form fields below the map gives a non-visual sense of the map coverage. The fields give approximate information on the east-west and north-south extents of the map, as well as the scale and width (in kilometres). See the notes right middle section above for advice on how to interpret these values. These form fields can be edited to force the map to be redrawn to specified values of geographic extent, scale or width, as described right lower section above .

Users should note that surveys can also be identified directly from the Surveys index table that lists every survey in the catalogue. This page allows the user to filter the list in ways that are very similar to those that are available via the index map.

Date modified:: 2024-09-23