Mosaic Preview
The Mosaic Preview shows progress toward a full mosaic of this item's content—as documents are georeferenced, they will automatically appear here.
You can also view this mosaic alongside all other mosaics for this locale: Frederick, Md.
Georeferencing Overview
The Georeferencing Overview provides a per-document summary and access point to the entire georeferencing process for this item's content. As documents are processed, they will move through the sections from top to bottom.
Unprepared
Each document in the Unprepared section must be evaluated individually, and, if it contains more than one mapped area, split into separate pieces.
Prepared
Content in the Prepared section is ready to be georeferenced. You can also decide here if a particular document should be moved to the Non-map Content section, for example if it is a title page or text index (this designation can be easily reversed).
Georeferenced
The Georeferenced section holds all content that has been spatially rectified, though you can still edit the control points for any layer whose georeferencing should be improved.
Use the Classify Layers button to sort layers into different categories, if applicable. For example, if a Key Map is present, classify it here so other interfaces will treat it appropriately.
MultiMask
The MultiMask is a mechanism for trimming the margins from every layer in a way that guarantees a seamless mosaic across this item's content.
How to create a MultiMask
- Use to start a mask for a particular layer.
- Use to delete an existing mask.
- Use to save your work (do this often!).
- Use to discard all changes since the last save.
Important Notes
- You must be signed in to save your work, so don't get started before you are signed in!
- The vertices of every adjacent mask should be snapped together
- You can drag existing vertices to snap them to others, but this is sometimes "sticky" and takes a couple of tries.
- If a mosaic is generated for this item, only layers that have been masked will be included in the mosaic.
Non-Map Content
The Non-Map Content section holds documents (or document fragments) that are not maps, like a title page or text index.
Access Settings
Access level: any
Any logged in users can georeference this item's content.
ready undefined undefined falseAre you sure this document does not need to be split?
Are you sure you want to remove all georeferencing information for this layer? This operation cannot be reversed, and is only necessary if the preparation step for this document needs to be redone.
If you only need to improve the ground control points for this layer, click edit georeferencing.
Download & Web Services
After multiple pages have been georeferenced and a multimask has been created, a single mosaic can be generated from all of this item's layers. Once created, the mosaic can be downloaded as a GeoTIFF, or integrated as a web service into any common GIS or web GIS software via the XYZ tiles URL.
How to use XYZ tiles in desktop software
How to use XYZ tiles on the web
Map Details
Title | Sanborn Map of FHA Block Data Map, Frederick, MD |
Year | 1928 |
Locale | Frederick, Md. |
Source | loc.gov/item/GMP8MS |
Contributors & Attribution
Initial load | -- |
Prep | 0 sheets prepared |
Georef | 0 georeferencing sessions |
Credit line: | Library of Congress, Geography and Map Division, Sanborn Maps Collection. |
Mosaic Download & Web Services
Only layers that have been trimmed in the MultiMask will appear in the mosaic. You can access untrimmed layers individually through the Georeferenced section.
Work History
When users complete a step in the georeferencing process, it is stored as a session, either a "preparation" session (P) or "georeference" sessions (G). (MultiMask trimming is not stored in sessions, for now.)
If you are looking for a list of the most recently added items (volumes), go to the items page and sort the table by Load date.
More sophisticated filter and sort capabilities for this list are in the works. This data is also accessible via the beta API. Please get in touch if you would like a key for the API.