At OHK Consultants, we specialize in providing strategic, innovative, and development solutions to our clients. Our goal is to help organizations achieve their objectives by offering customized services that are tailored to their specific needs. We offer strategy, intelligence, and innovation consul
data identification and collection steps are sometimes considered the most difficult and demanding aspects of GIS projects.
Data must be identified and collected for all relevant spatial and non-spatial data for a parcel level of interest. Spatial data might include the boundaries of the parcels, which can often be obtained from one entity in the local government and, in some cases, driven from recent satellite imagery. Non-spatial data could include property characteristics like the age of structures, building materials, square footage, and so forth, often found in property tax records. Let's break down the types of data you might need to collect for a comprehensive property valuation:
Property assessment: The methods vary by jurisdiction, but three primary methods are commonly used. First, the market approach values a property based on what similar properties have sold for in the same area, considering the property's location, size, condition, and features and the prices at which similar properties have recently sold. Second, the cost approach, often used for unique or special-purpose properties or new construction, values a property based on how much it would cost to replace it with an identical or similar property, taking into account the cost of materials and labor required to reproduce or replace the property, minus depreciation. Lastly, the income approach, typically used for investment or commercial properties, values a property based on its income. It calculates the net present value of future income streams given the yield an investor would expect for that investment. Depending on the property's nature and data availability, these methods can sometimes be combined. However, the specifics can vary greatly depending on local laws and practices, so it's best to contact the local assessor's office for the most accurate information. Each method would require different data collection: Each method of property assessment requires specific types of information or measurements to complete the evaluation:
Market Approach: For the market approach, the following measurements are typically required:
The recent sale prices of comparable properties in the same area.
Characteristics of the property, including the number of bedrooms and bathrooms, square footage, lot size, age, and the property's condition.
Cost Approach: For the cost approach, these measurements are needed:
The cost to construct a similar property, including labor and materials. This might require data on local construction costs and labor rates.
The value of the land as if it were vacant. This could be based on the sale prices of comparable land parcels in the same area.
The depreciation of the property could be due to physical wear and tear, functional obsolescence (e.g., an outdated layout), or external factors (e.g., changes in the neighborhood).
Income Approach: For the income approach, you would need:
The potential income the property could generate. For rental properties, this would be the potential rental income. For businesses, it could be the income the business generates.
The operating expenses of the property, such as maintenance, utilities, insurance, and property management costs.
The capitalization rate is the rate of return a reasonable investor would expect on the property type. This could be based on rates for comparable properties.
Data Type #1—Spatial Data—these data have a geographic component and are important for property valuation. Usually, they can be generated through GIS tools if not already available.
Parcel Boundaries: These are the specific outlines of each property. They typically come in the form of shapefiles and indicate the precise geographical boundaries of a property.
Future Development Plans: Information about any future infrastructure or development plans in the area. These could significantly impact the future value of a property.
Satellite Images: High-resolution satellite images can provide a lot of useful information about a property, including the size and shape of buildings, the presence of features like pools or solar panels, and the general condition of the property.
Topographic Data: This could include Digital Elevation Models (DEMs) that show the elevation of the land, which could affect property value.
Land Use Data: This shows how land in the area is used (residential, commercial, industrial, agricultural, etc.). Land use could have a significant impact on property values.
Road Networks: Proximity to transportation infrastructure can influence a property's value. This includes public transit data stations or stops, and proximity to public transportation can be a significant factor in property valuation.
Environmental Data: This might include flood zones, proximity to bodies of water, forest cover, soil quality, etc.
Amenities: Locations of schools, parks, shopping centers, hospitals, and other amenities.
Data Type #2—Non-Spatial Data—these are data that don't have a geographic component but are still important for property valuation:
Structural Characteristics: This might include the age of the buildings, their square footage, the number of rooms, the types of materials used, and other physical characteristics.
Building Codes Compliance: Details about the building's compliance with local codes can impact its value. This could include information about any code violations and the results of any inspections.
Rental History: If a property has been rented out in the past, information about the rental history can be useful. This could include the length of each rental period, the amount of rent charged, and the reliability of the tenants.
Ownership Details: This might include the owner's name, purchase date, purchase price, etc.
Sale History: Information about previous property sales, including dates and prices.
Tax Records: Past tax assessments and payments could be useful for predicting future tax amounts.
Local Market Data: Data about recent sales of comparable properties in the area.
Zoning Regulations: The property's zoning designation and what kind of structures or businesses are allowed there.
Environmental Efficiency Ratings: These can include ratings related to energy efficiency, such as LEED ratings or other environmental impacts of the property.
Disaster History: Information about any natural disasters that have affected the property. This could include floods, earthquakes, wildfires, etc.
Crime Statistics: Detailed data about the area's prevalence and types of crime can significantly impact a property's value.
Liens and Judgments: Any liens or judgments against the property could affect its marketability and value.
When collecting data, ensuring ISO or INSPIRE compliance for data can be important for interoperability, standardization, and data sharing. While it's crucial to consult the specific requirements of ISO or INSPIRE for your region or project, here are some general considerations for data formats and importing into open-source GIS software like QGIS.
Spatial Data Infrastructure (SDI) Considerations—ISO (International Organization for Standardization) standards play a critical role in guiding the creation and management of Spatial Data Infrastructure (SDI). Here's how the data could be formulated with references to relevant ISO standards:
Data Availability (ISO 19115: Metadata): According to this standard, there should be adequate metadata to describe the available spatial data for the required geographic areas. This ensures that users can find the appropriate datasets and understand their content, source, and usability.
Data Accuracy (ISO 19157: Data Quality): This standard provides a framework for specifying and reporting data quality, including accuracy. The SDI will ensure the spatial data is accurate and up-to-date, with quality measures implemented according to this standard.
Interoperability (ISO 19119: Services): This standard defines how GIS and ‘services’ interact. This assumes that there is an ambition to integrate with other systems used by tax authorities, for example—in such cases, the data can integrate effectively with other systems used by tax authorities, promoting seamless data sharing and usage.
Sustainability (ISO 19101: Reference Model): This standard provides a framework for establishing and maintaining an SDI. It will guide the project in ensuring the system is robust, maintained, and updated over time to remain relevant and useful.
Schematic Mapping of Existing Data: This process entails visualizing or representing existing spatial data in an organized, intuitive, and easily understandable format. This can include various geographic and spatial data an organization may have collected over time. It provides an overview of the current data situation and can help to identify patterns, relationships, or discrepancies that might not be readily apparent from raw data.
Schematic Mapping of Periodic Reports: Periodic reports contain valuable insights into temporal changes, trends, and patterns. Schematic mapping of such reports visually represents these insights over time, often revealing otherwise hidden temporal patterns or changes. This makes it easier for decision-makers to understand trends and make informed decisions.
Schematic Mapping of Scheme of Service of Selected Institutions: This pertains to the visual representation of how different services of an organization or institutions are interconnected spatially, how they function, and how they can influence one another. In an SDI context, it can map the flow of spatial data within and between organizations, highlighting any bottlenecks, inefficiencies, or potential areas for improvement.